In the Linux kernel, the following vulnerability has been resolved: x86/fpu: Fix copy_xstate_to_uabi() to copy init states correctly When an extended state component is not present in fpstate, but in init state, the function copies from init_fpstate via copy_feature(). But, dynamic states are not present in init_fpstate because of all-zeros init states. Then retrieving them from init_fpstate will explode like this: BUG: kernel NULL pointer dereference, address: 0000000000000000 ... RIP: 0010:memcpy_erms+0x6/0x10 ? __copy_xstate_to_uabi_buf+0x381/0x870 fpu_copy_guest_fpstate_to_uabi+0x28/0x80 kvm_arch_vcpu_ioctl+0x14c/0x1460 [kvm] ? __this_cpu_preempt_check+0x13/0x20 ? vmx_vcpu_put+0x2e/0x260 [kvm_intel] kvm_vcpu_ioctl+0xea/0x6b0 [kvm] ? kvm_vcpu_ioctl+0xea/0x6b0 [kvm] ? __fget_light+0xd4/0x130 __x64_sys_ioctl+0xe3/0x910 ? debug_smp_processor_id+0x17/0x20 ? fpregs_assert_state_consistent+0x27/0x50 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd Adjust the 'mask' to zero out the userspace buffer for the features that are not available both from fpstate and from init_fpstate. The dynamic features depend on the compacted XSAVE format. Ensure it is enabled before reading XCOMP_BV in init_fpstate.

In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: Validate BOOT record_size When the NTFS BOOT record_size field < 0, it represents a shift value. However, there is no sanity check on the shift result and the sbi->record_bits calculation through blksize_bits() assumes the size always > 256, which could lead to NPD while mounting a malformed NTFS image. [ 318.675159] BUG: kernel NULL pointer dereference, address: 0000000000000158 [ 318.675682] #PF: supervisor read access in kernel mode [ 318.675869] #PF: error_code(0x0000) - not-present page [ 318.676246] PGD 0 P4D 0 [ 318.676502] Oops: 0000 [#1] PREEMPT SMP NOPTI [ 318.676934] CPU: 0 PID: 259 Comm: mount Not tainted 5.19.0 #5 [ 318.677289] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 [ 318.678136] RIP: 0010:ni_find_attr+0x2d/0x1c0 [ 318.678656] Code: 89 ca 4d 89 c7 41 56 41 55 41 54 41 89 cc 55 48 89 fd 53 48 89 d3 48 83 ec 20 65 48 8b 04 25 28 00 00 00 48 89 44 24 180 [ 318.679848] RSP: 0018:ffffa6c8c0297bd8 EFLAGS: 00000246 [ 318.680104] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000080 [ 318.680790] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 318.681679] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 318.682577] R10: 0000000000000000 R11: 0000000000000005 R12: 0000000000000080 [ 318.683015] R13: ffff8d5582e68400 R14: 0000000000000100 R15: 0000000000000000 [ 318.683618] FS: 00007fd9e1c81e40(0000) GS:ffff8d55fdc00000(0000) knlGS:0000000000000000 [ 318.684280] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 318.684651] CR2: 0000000000000158 CR3: 0000000002e1a000 CR4: 00000000000006f0 [ 318.685623] Call Trace: [ 318.686607] <TASK> [ 318.686872] ? ntfs_alloc_inode+0x1a/0x60 [ 318.687235] attr_load_runs_vcn+0x2b/0xa0 [ 318.687468] mi_read+0xbb/0x250 [ 318.687576] ntfs_iget5+0x114/0xd90 [ 318.687750] ntfs_fill_super+0x588/0x11b0 [ 318.687953] ? put_ntfs+0x130/0x130 [ 318.688065] ? snprintf+0x49/0x70 [ 318.688164] ? put_ntfs+0x130/0x130 [ 318.688256] get_tree_bdev+0x16a/0x260 [ 318.688407] vfs_get_tree+0x20/0xb0 [ 318.688519] path_mount+0x2dc/0x9b0 [ 318.688877] do_mount+0x74/0x90 [ 318.689142] __x64_sys_mount+0x89/0xd0 [ 318.689636] do_syscall_64+0x3b/0x90 [ 318.689998] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 318.690318] RIP: 0033:0x7fd9e133c48a [ 318.690687] Code: 48 8b 0d 11 fa 2a 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 008 [ 318.691357] RSP: 002b:00007ffd374406c8 EFLAGS: 00000202 ORIG_RAX: 00000000000000a5 [ 318.691632] RAX: ffffffffffffffda RBX: 0000564d0b051080 RCX: 00007fd9e133c48a [ 318.691920] RDX: 0000564d0b051280 RSI: 0000564d0b051300 RDI: 0000564d0b0596a0 [ 318.692123] RBP: 0000000000000000 R08: 0000564d0b0512a0 R09: 0000000000000020 [ 318.692349] R10: 00000000c0ed0000 R11: 0000000000000202 R12: 0000564d0b0596a0 [ 318.692673] R13: 0000564d0b051280 R14: 0000000000000000 R15: 00000000ffffffff [ 318.693007] </TASK> [ 318.693271] Modules linked in: [ 318.693614] CR2: 0000000000000158 [ 318.694446] ---[ end trace 0000000000000000 ]--- [ 318.694779] RIP: 0010:ni_find_attr+0x2d/0x1c0 [ 318.694952] Code: 89 ca 4d 89 c7 41 56 41 55 41 54 41 89 cc 55 48 89 fd 53 48 89 d3 48 83 ec 20 65 48 8b 04 25 28 00 00 00 48 89 44 24 180 [ 318.696042] RSP: 0018:ffffa6c8c0297bd8 EFLAGS: 00000246 [ 318.696531] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000080 [ 318.698114] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [ 318.699286] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 318.699795] R10: 0000000000000000 R11: 0000000000000005 R12: 0000000000000080 [ 318.700236] R13: ffff8d5582e68400 R14: 0000000000000100 R15: 0000000000000000 [ 318.700973] FS: 00007fd9e1c81e40(0000) GS:ffff8d55fdc00000(0000) knlGS:0000000000000000 [ ---truncated---

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_conn: Fix crash on hci_create_cis_sync When attempting to connect multiple ISO sockets without using DEFER_SETUP may result in the following crash: BUG: KASAN: null-ptr-deref in hci_create_cis_sync+0x18b/0x2b0 Read of size 2 at addr 0000000000000036 by task kworker/u3:1/50 CPU: 0 PID: 50 Comm: kworker/u3:1 Not tainted 6.0.0-rc7-02243-gb84a13ff4eda #4373 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-1.fc36 04/01/2014 Workqueue: hci0 hci_cmd_sync_work Call Trace: <TASK> dump_stack_lvl+0x19/0x27 kasan_report+0xbc/0xf0 ? hci_create_cis_sync+0x18b/0x2b0 hci_create_cis_sync+0x18b/0x2b0 ? get_link_mode+0xd0/0xd0 ? __ww_mutex_lock_slowpath+0x10/0x10 ? mutex_lock+0xe0/0xe0 ? get_link_mode+0xd0/0xd0 hci_cmd_sync_work+0x111/0x190 process_one_work+0x427/0x650 worker_thread+0x87/0x750 ? process_one_work+0x650/0x650 kthread+0x14e/0x180 ? kthread_exit+0x50/0x50 ret_from_fork+0x22/0x30 </TASK>

In the Linux kernel, the following vulnerability has been resolved: tracing/eprobes: Have event probes be consistent with kprobes and uprobes Currently, if a symbol "@" is attempted to be used with an event probe (eprobes), it will cause a NULL pointer dereference crash. Both kprobes and uprobes can reference data other than the main registers. Such as immediate address, symbols and the current task name. Have eprobes do the same thing. For "comm", if "comm" is used and the event being attached to does not have the "comm" field, then make it the "$comm" that kprobes has. This is consistent to the way histograms and filters work.

In the Linux kernel, the following vulnerability has been resolved: iommu/mediatek: Check return value after calling platform_get_resource() platform_get_resource() may return NULL pointer, we need check its return value to avoid null-ptr-deref in resource_size().

In the Linux kernel, the following vulnerability has been resolved: kprobes: Fix check for probe enabled in kill_kprobe() In kill_kprobe(), the check whether disarm_kprobe_ftrace() needs to be called always fails. This is because before that we set the KPROBE_FLAG_GONE flag for kprobe so that "!kprobe_disabled(p)" is always false. The disarm_kprobe_ftrace() call introduced by commit: 0cb2f1372baa ("kprobes: Fix NULL pointer dereference at kprobe_ftrace_handler") to fix the NULL pointer reference problem. When the probe is enabled, if we do not disarm it, this problem still exists. Fix it by putting the probe enabled check before setting the KPROBE_FLAG_GONE flag.

In the Linux kernel, the following vulnerability has been resolved: media: dvb-usb-v2: af9035: Fix null-ptr-deref in af9035_i2c_master_xfer In af9035_i2c_master_xfer, msg is controlled by user. When msg[i].buf is null and msg[i].len is zero, former checks on msg[i].buf would be passed. Malicious data finally reach af9035_i2c_master_xfer. If accessing msg[i].buf[0] without sanity check, null ptr deref would happen. We add check on msg[i].len to prevent crash. Similar commit: commit 0ed554fd769a ("media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer()")

In the Linux kernel, the following vulnerability has been resolved: BPF: Fix potential bad pointer dereference in bpf_sys_bpf() The bpf_sys_bpf() helper function allows an eBPF program to load another eBPF program from within the kernel. In this case the argument union bpf_attr pointer (as well as the insns and license pointers inside) is a kernel address instead of a userspace address (which is the case of a usual bpf() syscall). To make the memory copying process in the syscall work in both cases, bpfptr_t was introduced to wrap around the pointer and distinguish its origin. Specifically, when copying memory contents from a bpfptr_t, a copy_from_user() is performed in case of a userspace address and a memcpy() is performed for a kernel address. This can lead to problems because the in-kernel pointer is never checked for validity. The problem happens when an eBPF syscall program tries to call bpf_sys_bpf() to load a program but provides a bad insns pointer -- say 0xdeadbeef -- in the bpf_attr union. The helper calls __sys_bpf() which would then call bpf_prog_load() to load the program. bpf_prog_load() is responsible for copying the eBPF instructions to the newly allocated memory for the program; it creates a kernel bpfptr_t for insns and invokes copy_from_bpfptr(). Internally, all bpfptr_t operations are backed by the corresponding sockptr_t operations, which performs direct memcpy() on kernel pointers for copy_from/strncpy_from operations. Therefore, the code is always happy to dereference the bad pointer to trigger a un-handle-able page fault and in turn an oops. However, this is not supposed to happen because at that point the eBPF program is already verified and should not cause a memory error. Sample KASAN trace: [ 25.685056][ T228] ================================================================== [ 25.685680][ T228] BUG: KASAN: user-memory-access in copy_from_bpfptr+0x21/0x30 [ 25.686210][ T228] Read of size 80 at addr 00000000deadbeef by task poc/228 [ 25.686732][ T228] [ 25.686893][ T228] CPU: 3 PID: 228 Comm: poc Not tainted 5.19.0-rc7 #7 [ 25.687375][ T228] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS d55cb5a 04/01/2014 [ 25.687991][ T228] Call Trace: [ 25.688223][ T228] <TASK> [ 25.688429][ T228] dump_stack_lvl+0x73/0x9e [ 25.688747][ T228] print_report+0xea/0x200 [ 25.689061][ T228] ? copy_from_bpfptr+0x21/0x30 [ 25.689401][ T228] ? _printk+0x54/0x6e [ 25.689693][ T228] ? _raw_spin_lock_irqsave+0x70/0xd0 [ 25.690071][ T228] ? copy_from_bpfptr+0x21/0x30 [ 25.690412][ T228] kasan_report+0xb5/0xe0 [ 25.690716][ T228] ? copy_from_bpfptr+0x21/0x30 [ 25.691059][ T228] kasan_check_range+0x2bd/0x2e0 [ 25.691405][ T228] ? copy_from_bpfptr+0x21/0x30 [ 25.691734][ T228] memcpy+0x25/0x60 [ 25.692000][ T228] copy_from_bpfptr+0x21/0x30 [ 25.692328][ T228] bpf_prog_load+0x604/0x9e0 [ 25.692653][ T228] ? cap_capable+0xb4/0xe0 [ 25.692956][ T228] ? security_capable+0x4f/0x70 [ 25.693324][ T228] __sys_bpf+0x3af/0x580 [ 25.693635][ T228] bpf_sys_bpf+0x45/0x240 [ 25.693937][ T228] bpf_prog_f0ec79a5a3caca46_bpf_func1+0xa2/0xbd [ 25.694394][ T228] bpf_prog_run_pin_on_cpu+0x2f/0xb0 [ 25.694756][ T228] bpf_prog_test_run_syscall+0x146/0x1c0 [ 25.695144][ T228] bpf_prog_test_run+0x172/0x190 [ 25.695487][ T228] __sys_bpf+0x2c5/0x580 [ 25.695776][ T228] __x64_sys_bpf+0x3a/0x50 [ 25.696084][ T228] do_syscall_64+0x60/0x90 [ 25.696393][ T228] ? fpregs_assert_state_consistent+0x50/0x60 [ 25.696815][ T228] ? exit_to_user_mode_prepare+0x36/0xa0 [ 25.697202][ T228] ? syscall_exit_to_user_mode+0x20/0x40 [ 25.697586][ T228] ? do_syscall_64+0x6e/0x90 [ 25.697899][ T228] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 25.698312][ T228] RIP: 0033:0x7f6d543fb759 [ 25.698624][ T228] Code: 08 5b 89 e8 5d c3 66 2e 0f 1f 84 00 00 00 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d ---truncated---

In the Linux kernel, the following vulnerability has been resolved: drm/ttm: Fix dummy res NULL ptr deref bug Check the bo->resource value before accessing the resource mem_type. v2: Fix commit description unwrapped warning <log snip> [ 40.191227][ T184] general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN PTI [ 40.192995][ T184] KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] [ 40.194411][ T184] CPU: 1 PID: 184 Comm: systemd-udevd Not tainted 5.19.0-rc4-00721-gb297c22b7070 #1 [ 40.196063][ T184] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-4 04/01/2014 [ 40.199605][ T184] RIP: 0010:ttm_bo_validate+0x1b3/0x240 [ttm] [ 40.200754][ T184] Code: e8 72 c5 ff ff 83 f8 b8 74 d4 85 c0 75 54 49 8b 9e 58 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d 7b 10 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 04 3c 03 7e 44 8b 53 10 31 c0 85 d2 0f 85 58 [ 40.203685][ T184] RSP: 0018:ffffc900006df0c8 EFLAGS: 00010202 [ 40.204630][ T184] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 1ffff1102f4bb71b [ 40.205864][ T184] RDX: 0000000000000002 RSI: ffffc900006df208 RDI: 0000000000000010 [ 40.207102][ T184] RBP: 1ffff920000dbe1a R08: ffffc900006df208 R09: 0000000000000000 [ 40.208394][ T184] R10: ffff88817a5f0000 R11: 0000000000000001 R12: ffffc900006df110 [ 40.209692][ T184] R13: ffffc900006df0f0 R14: ffff88817a5db800 R15: ffffc900006df208 [ 40.210862][ T184] FS: 00007f6b1d16e8c0(0000) GS:ffff88839d700000(0000) knlGS:0000000000000000 [ 40.212250][ T184] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 40.213275][ T184] CR2: 000055a1001d4ff0 CR3: 00000001700f4000 CR4: 00000000000006e0 [ 40.214469][ T184] Call Trace: [ 40.214974][ T184] <TASK> [ 40.215438][ T184] ? ttm_bo_bounce_temp_buffer+0x140/0x140 [ttm] [ 40.216572][ T184] ? mutex_spin_on_owner+0x240/0x240 [ 40.217456][ T184] ? drm_vma_offset_add+0xaa/0x100 [drm] [ 40.218457][ T184] ttm_bo_init_reserved+0x3d6/0x540 [ttm] [ 40.219410][ T184] ? shmem_get_inode+0x744/0x980 [ 40.220231][ T184] ttm_bo_init_validate+0xb1/0x200 [ttm] [ 40.221172][ T184] ? bo_driver_evict_flags+0x340/0x340 [drm_vram_helper] [ 40.222530][ T184] ? ttm_bo_init_reserved+0x540/0x540 [ttm] [ 40.223643][ T184] ? __do_sys_finit_module+0x11a/0x1c0 [ 40.224654][ T184] ? __shmem_file_setup+0x102/0x280 [ 40.234764][ T184] drm_gem_vram_create+0x305/0x480 [drm_vram_helper] [ 40.235766][ T184] ? bo_driver_evict_flags+0x340/0x340 [drm_vram_helper] [ 40.236846][ T184] ? __kasan_slab_free+0x108/0x180 [ 40.237650][ T184] drm_gem_vram_fill_create_dumb+0x134/0x340 [drm_vram_helper] [ 40.238864][ T184] ? local_pci_probe+0xdf/0x180 [ 40.239674][ T184] ? drmm_vram_helper_init+0x400/0x400 [drm_vram_helper] [ 40.240826][ T184] drm_client_framebuffer_create+0x19c/0x400 [drm] [ 40.241955][ T184] ? drm_client_buffer_delete+0x200/0x200 [drm] [ 40.243001][ T184] ? drm_client_pick_crtcs+0x554/0xb80 [drm] [ 40.244030][ T184] drm_fb_helper_generic_probe+0x23f/0x940 [drm_kms_helper] [ 40.245226][ T184] ? __cond_resched+0x1c/0xc0 [ 40.245987][ T184] ? drm_fb_helper_memory_range_to_clip+0x180/0x180 [drm_kms_helper] [ 40.247316][ T184] ? mutex_unlock+0x80/0x100 [ 40.248005][ T184] ? __mutex_unlock_slowpath+0x2c0/0x2c0 [ 40.249083][ T184] drm_fb_helper_single_fb_probe+0x907/0xf00 [drm_kms_helper] [ 40.250314][ T184] ? drm_fb_helper_check_var+0x1180/0x1180 [drm_kms_helper] [ 40.251540][ T184] ? __cond_resched+0x1c/0xc0 [ 40.252321][ T184] ? mutex_lock+0x9f/0x100 [ 40.253062][ T184] __drm_fb_helper_initial_config_and_unlock+0xb9/0x2c0 [drm_kms_helper] [ 40.254394][ T184] drm_fbdev_client_hotplug+0x56f/0x840 [drm_kms_helper] [ 40.255477][ T184] drm_fbdev_generic_setup+0x165/0x3c0 [drm_kms_helper] [ 40.256607][ T184] bochs_pci_probe+0x6b7/0x900 [bochs] [ ---truncated---

In the Linux kernel, the following vulnerability has been resolved: ext4: fix null-ptr-deref in ext4_write_info I caught a null-ptr-deref bug as follows: ================================================================== KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f] CPU: 1 PID: 1589 Comm: umount Not tainted 5.10.0-02219-dirty #339 RIP: 0010:ext4_write_info+0x53/0x1b0 [...] Call Trace: dquot_writeback_dquots+0x341/0x9a0 ext4_sync_fs+0x19e/0x800 __sync_filesystem+0x83/0x100 sync_filesystem+0x89/0xf0 generic_shutdown_super+0x79/0x3e0 kill_block_super+0xa1/0x110 deactivate_locked_super+0xac/0x130 deactivate_super+0xb6/0xd0 cleanup_mnt+0x289/0x400 __cleanup_mnt+0x16/0x20 task_work_run+0x11c/0x1c0 exit_to_user_mode_prepare+0x203/0x210 syscall_exit_to_user_mode+0x5b/0x3a0 do_syscall_64+0x59/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xa9 ================================================================== Above issue may happen as follows: ------------------------------------- exit_to_user_mode_prepare task_work_run __cleanup_mnt cleanup_mnt deactivate_super deactivate_locked_super kill_block_super generic_shutdown_super shrink_dcache_for_umount dentry = sb->s_root sb->s_root = NULL <--- Here set NULL sync_filesystem __sync_filesystem sb->s_op->sync_fs > ext4_sync_fs dquot_writeback_dquots sb->dq_op->write_info > ext4_write_info ext4_journal_start(d_inode(sb->s_root), EXT4_HT_QUOTA, 2) d_inode(sb->s_root) s_root->d_inode <--- Null pointer dereference To solve this problem, we use ext4_journal_start_sb directly to avoid s_root being used.

In the Linux kernel, the following vulnerability has been resolved: ACPI: processor: idle: Check acpi_fetch_acpi_dev() return value The return value of acpi_fetch_acpi_dev() could be NULL, which would cause a NULL pointer dereference to occur in acpi_device_hid(). [ rjw: Subject and changelog edits, added empty line after if () ]

In the Linux kernel, the following vulnerability has been resolved: mmc: moxart: fix return value check of mmc_add_host() mmc_add_host() may return error, if we ignore its return value, the memory that allocated in mmc_alloc_host() will be leaked and it will lead a kernel crash because of deleting not added device in the remove path. So fix this by checking the return value and goto error path which will call mmc_free_host().

In the Linux kernel, the following vulnerability has been resolved: drm/amdkfd: Fix kfd_process_device_init_vm error handling Should only destroy the ib_mem and let process cleanup worker to free the outstanding BOs. Reset the pointer in pdd->qpd structure, to avoid NULL pointer access in process destroy worker. BUG: kernel NULL pointer dereference, address: 0000000000000010 Call Trace: amdgpu_amdkfd_gpuvm_unmap_gtt_bo_from_kernel+0x46/0xb0 [amdgpu] kfd_process_device_destroy_cwsr_dgpu+0x40/0x70 [amdgpu] kfd_process_destroy_pdds+0x71/0x190 [amdgpu] kfd_process_wq_release+0x2a2/0x3b0 [amdgpu] process_one_work+0x2a1/0x600 worker_thread+0x39/0x3d0

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: rfcomm: Fix null-ptr-deref in rfcomm_check_security During our fuzz testing of the connection and disconnection process at the RFCOMM layer, we discovered this bug. By comparing the packets from a normal connection and disconnection process with the testcase that triggered a KASAN report. We analyzed the cause of this bug as follows: 1. In the packets captured during a normal connection, the host sends a `Read Encryption Key Size` type of `HCI_CMD` packet (Command Opcode: 0x1408) to the controller to inquire the length of encryption key.After receiving this packet, the controller immediately replies with a Command Completepacket (Event Code: 0x0e) to return the Encryption Key Size. 2. In our fuzz test case, the timing of the controller's response to this packet was delayed to an unexpected point: after the RFCOMM and L2CAP layers had disconnected but before the HCI layer had disconnected. 3. After receiving the Encryption Key Size Response at the time described in point 2, the host still called the rfcomm_check_security function. However, by this time `struct l2cap_conn *conn = l2cap_pi(sk)->chan->conn;` had already been released, and when the function executed `return hci_conn_security(conn->hcon, d->sec_level, auth_type, d->out);`, specifically when accessing `conn->hcon`, a null-ptr-deref error occurred. To fix this bug, check if `sk->sk_state` is BT_CLOSED before calling rfcomm_recv_frame in rfcomm_process_rx.

In the Linux kernel, the following vulnerability has been resolved: cxl: fix possible null-ptr-deref in cxl_pci_init_afu|adapter() If device_register() fails in cxl_pci_afu|adapter(), the device is not added, device_unregister() can not be called in the error path, otherwise it will cause a null-ptr-deref because of removing not added device. As comment of device_register() says, it should use put_device() to give up the reference in the error path. So split device_unregister() into device_del() and put_device(), then goes to put dev when register fails.

In the Linux kernel, the following vulnerability has been resolved: drbd: only clone bio if we have a backing device Commit c347a787e34cb (drbd: set ->bi_bdev in drbd_req_new) moved a bio_set_dev call (which has since been removed) to "earlier", from drbd_request_prepare to drbd_req_new. The problem is that this accesses device->ldev->backing_bdev, which is not NULL-checked at this point. When we don't have an ldev (i.e. when the DRBD device is diskless), this leads to a null pointer deref. So, only allocate the private_bio if we actually have a disk. This is also a small optimization, since we don't clone the bio to only to immediately free it again in the diskless case.

In the Linux kernel, the following vulnerability has been resolved: net: If sock is dead don't access sock's sk_wq in sk_stream_wait_memory Fixes the below NULL pointer dereference: [...] [ 14.471200] Call Trace: [ 14.471562] <TASK> [ 14.471882] lock_acquire+0x245/0x2e0 [ 14.472416] ? remove_wait_queue+0x12/0x50 [ 14.473014] ? _raw_spin_lock_irqsave+0x17/0x50 [ 14.473681] _raw_spin_lock_irqsave+0x3d/0x50 [ 14.474318] ? remove_wait_queue+0x12/0x50 [ 14.474907] remove_wait_queue+0x12/0x50 [ 14.475480] sk_stream_wait_memory+0x20d/0x340 [ 14.476127] ? do_wait_intr_irq+0x80/0x80 [ 14.476704] do_tcp_sendpages+0x287/0x600 [ 14.477283] tcp_bpf_push+0xab/0x260 [ 14.477817] tcp_bpf_sendmsg_redir+0x297/0x500 [ 14.478461] ? __local_bh_enable_ip+0x77/0xe0 [ 14.479096] tcp_bpf_send_verdict+0x105/0x470 [ 14.479729] tcp_bpf_sendmsg+0x318/0x4f0 [ 14.480311] sock_sendmsg+0x2d/0x40 [ 14.480822] ____sys_sendmsg+0x1b4/0x1c0 [ 14.481390] ? copy_msghdr_from_user+0x62/0x80 [ 14.482048] ___sys_sendmsg+0x78/0xb0 [ 14.482580] ? vmf_insert_pfn_prot+0x91/0x150 [ 14.483215] ? __do_fault+0x2a/0x1a0 [ 14.483738] ? do_fault+0x15e/0x5d0 [ 14.484246] ? __handle_mm_fault+0x56b/0x1040 [ 14.484874] ? lock_is_held_type+0xdf/0x130 [ 14.485474] ? find_held_lock+0x2d/0x90 [ 14.486046] ? __sys_sendmsg+0x41/0x70 [ 14.486587] __sys_sendmsg+0x41/0x70 [ 14.487105] ? intel_pmu_drain_pebs_core+0x350/0x350 [ 14.487822] do_syscall_64+0x34/0x80 [ 14.488345] entry_SYSCALL_64_after_hwframe+0x63/0xcd [...] The test scenario has the following flow: thread1 thread2 ----------- --------------- tcp_bpf_sendmsg tcp_bpf_send_verdict tcp_bpf_sendmsg_redir sock_close tcp_bpf_push_locked __sock_release tcp_bpf_push //inet_release do_tcp_sendpages sock->ops->release sk_stream_wait_memory // tcp_close sk_wait_event sk->sk_prot->close release_sock(__sk); *** lock_sock(sk); __tcp_close sock_orphan(sk) sk->sk_wq = NULL release_sock **** lock_sock(__sk); remove_wait_queue(sk_sleep(sk), &wait); sk_sleep(sk) //NULL pointer dereference &rcu_dereference_raw(sk->sk_wq)->wait While waiting for memory in thread1, the socket is released with its wait queue because thread2 has closed it. This caused by tcp_bpf_send_verdict didn't increase the f_count of psock->sk_redir->sk_socket->file in thread1. We should check if SOCK_DEAD flag is set on wakeup in sk_stream_wait_memory before accessing the wait queue.

In the Linux kernel, the following vulnerability has been resolved: clk: Fix clk_core_get NULL dereference It is possible for clk_core_get to dereference a NULL in the following sequence: clk_core_get() of_clk_get_hw_from_clkspec() __of_clk_get_hw_from_provider() __clk_get_hw() __clk_get_hw() can return NULL which is dereferenced by clk_core_get() at hw->core. Prior to commit dde4eff47c82 ("clk: Look for parents with clkdev based clk_lookups") the check IS_ERR_OR_NULL() was performed which would have caught the NULL. Reading the description of this function it talks about returning NULL but that cannot be so at the moment. Update the function to check for hw before dereferencing it and return NULL if hw is NULL.

In the Linux kernel, the following vulnerability has been resolved: phy: ti: phy-omap-usb2: Fix NULL pointer dereference for SRP If the external phy working together with phy-omap-usb2 does not implement send_srp(), we may still attempt to call it. This can happen on an idle Ethernet gadget triggering a wakeup for example: configfs-gadget.g1 gadget.0: ECM Suspend configfs-gadget.g1 gadget.0: Port suspended. Triggering wakeup ... Unable to handle kernel NULL pointer dereference at virtual address 00000000 when execute ... PC is at 0x0 LR is at musb_gadget_wakeup+0x1d4/0x254 [musb_hdrc] ... musb_gadget_wakeup [musb_hdrc] from usb_gadget_wakeup+0x1c/0x3c [udc_core] usb_gadget_wakeup [udc_core] from eth_start_xmit+0x3b0/0x3d4 [u_ether] eth_start_xmit [u_ether] from dev_hard_start_xmit+0x94/0x24c dev_hard_start_xmit from sch_direct_xmit+0x104/0x2e4 sch_direct_xmit from __dev_queue_xmit+0x334/0xd88 __dev_queue_xmit from arp_solicit+0xf0/0x268 arp_solicit from neigh_probe+0x54/0x7c neigh_probe from __neigh_event_send+0x22c/0x47c __neigh_event_send from neigh_resolve_output+0x14c/0x1c0 neigh_resolve_output from ip_finish_output2+0x1c8/0x628 ip_finish_output2 from ip_send_skb+0x40/0xd8 ip_send_skb from udp_send_skb+0x124/0x340 udp_send_skb from udp_sendmsg+0x780/0x984 udp_sendmsg from __sys_sendto+0xd8/0x158 __sys_sendto from ret_fast_syscall+0x0/0x58 Let's fix the issue by checking for send_srp() and set_vbus() before calling them. For USB peripheral only cases these both could be NULL.

In the Linux kernel, the following vulnerability has been resolved: net: dsa: felix: suppress non-changes to the tagging protocol The way in which dsa_tree_change_tag_proto() works is that when dsa_tree_notify() fails, it doesn't know whether the operation failed mid way in a multi-switch tree, or it failed for a single-switch tree. So even though drivers need to fail cleanly in ds->ops->change_tag_protocol(), DSA will still call dsa_tree_notify() again, to restore the old tag protocol for potential switches in the tree where the change did succeeed (before failing for others). This means for the felix driver that if we report an error in felix_change_tag_protocol(), we'll get another call where proto_ops == old_proto_ops. If we proceed to act upon that, we may do unexpected things. For example, we will call dsa_tag_8021q_register() twice in a row, without any dsa_tag_8021q_unregister() in between. Then we will actually call dsa_tag_8021q_unregister() via old_proto_ops->teardown, which (if it manages to run at all, after walking through corrupted data structures) will leave the ports inoperational anyway. The bug can be readily reproduced if we force an error while in tag_8021q mode; this crashes the kernel. echo ocelot-8021q > /sys/class/net/eno2/dsa/tagging echo edsa > /sys/class/net/eno2/dsa/tagging # -EPROTONOSUPPORT Unable to handle kernel NULL pointer dereference at virtual address 0000000000000014 Call trace: vcap_entry_get+0x24/0x124 ocelot_vcap_filter_del+0x198/0x270 felix_tag_8021q_vlan_del+0xd4/0x21c dsa_switch_tag_8021q_vlan_del+0x168/0x2cc dsa_switch_event+0x68/0x1170 dsa_tree_notify+0x14/0x34 dsa_port_tag_8021q_vlan_del+0x84/0x110 dsa_tag_8021q_unregister+0x15c/0x1c0 felix_tag_8021q_teardown+0x16c/0x180 felix_change_tag_protocol+0x1bc/0x230 dsa_switch_event+0x14c/0x1170 dsa_tree_change_tag_proto+0x118/0x1c0

In the Linux kernel, the following vulnerability has been resolved: io_uring/msg_ring: Fix NULL pointer dereference in io_msg_send_fd() Syzkaller produced the below call trace: BUG: KASAN: null-ptr-deref in io_msg_ring+0x3cb/0x9f0 Write of size 8 at addr 0000000000000070 by task repro/16399 CPU: 0 PID: 16399 Comm: repro Not tainted 6.1.0-rc1 #28 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 Call Trace: <TASK> dump_stack_lvl+0xcd/0x134 ? io_msg_ring+0x3cb/0x9f0 kasan_report+0xbc/0xf0 ? io_msg_ring+0x3cb/0x9f0 kasan_check_range+0x140/0x190 io_msg_ring+0x3cb/0x9f0 ? io_msg_ring_prep+0x300/0x300 io_issue_sqe+0x698/0xca0 io_submit_sqes+0x92f/0x1c30 __do_sys_io_uring_enter+0xae4/0x24b0 .... RIP: 0033:0x7f2eaf8f8289 RSP: 002b:00007fff40939718 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f2eaf8f8289 RDX: 0000000000000000 RSI: 0000000000006f71 RDI: 0000000000000004 RBP: 00007fff409397a0 R08: 0000000000000000 R09: 0000000000000039 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004006d0 R13: 00007fff40939880 R14: 0000000000000000 R15: 0000000000000000 </TASK> Kernel panic - not syncing: panic_on_warn set ... We don't have a NULL check on file_ptr in io_msg_send_fd() function, so when file_ptr is NUL src_file is also NULL and get_file() dereferences a NULL pointer and leads to above crash. Add a NULL check to fix this issue.

In the Linux kernel, the following vulnerability has been resolved: md: fix a crash in mempool_free There's a crash in mempool_free when running the lvm test shell/lvchange-rebuild-raid.sh. The reason for the crash is this: * super_written calls atomic_dec_and_test(&mddev->pending_writes) and wake_up(&mddev->sb_wait). Then it calls rdev_dec_pending(rdev, mddev) and bio_put(bio). * so, the process that waited on sb_wait and that is woken up is racing with bio_put(bio). * if the process wins the race, it calls bioset_exit before bio_put(bio) is executed. * bio_put(bio) attempts to free a bio into a destroyed bio set - causing a crash in mempool_free. We fix this bug by moving bio_put before atomic_dec_and_test. We also move rdev_dec_pending before atomic_dec_and_test as suggested by Neil Brown. The function md_end_flush has a similar bug - we must call bio_put before we decrement the number of in-progress bios. BUG: kernel NULL pointer dereference, address: 0000000000000000 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 11557f0067 P4D 11557f0067 PUD 0 Oops: 0002 [#1] PREEMPT SMP CPU: 0 PID: 73 Comm: kworker/0:1 Not tainted 6.1.0-rc3 #5 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 Workqueue: kdelayd flush_expired_bios [dm_delay] RIP: 0010:mempool_free+0x47/0x80 Code: 48 89 ef 5b 5d ff e0 f3 c3 48 89 f7 e8 32 45 3f 00 48 63 53 08 48 89 c6 3b 53 04 7d 2d 48 8b 43 10 8d 4a 01 48 89 df 89 4b 08 <48> 89 2c d0 e8 b0 45 3f 00 48 8d 7b 30 5b 5d 31 c9 ba 01 00 00 00 RSP: 0018:ffff88910036bda8 EFLAGS: 00010093 RAX: 0000000000000000 RBX: ffff8891037b65d8 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 0000000000000202 RDI: ffff8891037b65d8 RBP: ffff8891447ba240 R08: 0000000000012908 R09: 00000000003d0900 R10: 0000000000000000 R11: 0000000000173544 R12: ffff889101a14000 R13: ffff8891562ac300 R14: ffff889102b41440 R15: ffffe8ffffa00d05 FS: 0000000000000000(0000) GS:ffff88942fa00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000001102e99000 CR4: 00000000000006b0 Call Trace: <TASK> clone_endio+0xf4/0x1c0 [dm_mod] clone_endio+0xf4/0x1c0 [dm_mod] __submit_bio+0x76/0x120 submit_bio_noacct_nocheck+0xb6/0x2a0 flush_expired_bios+0x28/0x2f [dm_delay] process_one_work+0x1b4/0x300 worker_thread+0x45/0x3e0 ? rescuer_thread+0x380/0x380 kthread+0xc2/0x100 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30 </TASK> Modules linked in: brd dm_delay dm_raid dm_mod af_packet uvesafb cfbfillrect cfbimgblt cn cfbcopyarea fb font fbdev tun autofs4 binfmt_misc configfs ipv6 virtio_rng virtio_balloon rng_core virtio_net pcspkr net_failover failover qemu_fw_cfg button mousedev raid10 raid456 libcrc32c async_raid6_recov async_memcpy async_pq raid6_pq async_xor xor async_tx raid1 raid0 md_mod sd_mod t10_pi crc64_rocksoft crc64 virtio_scsi scsi_mod evdev psmouse bsg scsi_common [last unloaded: brd] CR2: 0000000000000000 ---[ end trace 0000000000000000 ]---

In the Linux kernel, the following vulnerability has been resolved: iommu/vt-d: Fix NULL domain on device release In the kdump kernel, the IOMMU operates in deferred_attach mode. In this mode, info->domain may not yet be assigned by the time the release_device function is called. It leads to the following crash in the crash kernel: BUG: kernel NULL pointer dereference, address: 000000000000003c ... RIP: 0010:do_raw_spin_lock+0xa/0xa0 ... _raw_spin_lock_irqsave+0x1b/0x30 intel_iommu_release_device+0x96/0x170 iommu_deinit_device+0x39/0xf0 __iommu_group_remove_device+0xa0/0xd0 iommu_bus_notifier+0x55/0xb0 notifier_call_chain+0x5a/0xd0 blocking_notifier_call_chain+0x41/0x60 bus_notify+0x34/0x50 device_del+0x269/0x3d0 pci_remove_bus_device+0x77/0x100 p2sb_bar+0xae/0x1d0 ... i801_probe+0x423/0x740 Use the release_domain mechanism to fix it. The scalable mode context entry which is not part of release domain should be cleared in release_device().

In the Linux kernel, the following vulnerability has been resolved: cxl: fix possible null-ptr-deref in cxl_guest_init_afu|adapter() If device_register() fails in cxl_register_afu|adapter(), the device is not added, device_unregister() can not be called in the error path, otherwise it will cause a null-ptr-deref because of removing not added device. As comment of device_register() says, it should use put_device() to give up the reference in the error path. So split device_unregister() into device_del() and put_device(), then goes to put dev when register fails.

In the Linux kernel, the following vulnerability has been resolved: IB/IPoIB: Fix legacy IPoIB due to wrong number of queues The cited commit creates child PKEY interfaces over netlink will multiple tx and rx queues, but some devices doesn't support more than 1 tx and 1 rx queues. This causes to a crash when traffic is sent over the PKEY interface due to the parent having a single queue but the child having multiple queues. This patch fixes the number of queues to 1 for legacy IPoIB at the earliest possible point in time. BUG: kernel NULL pointer dereference, address: 000000000000036b PGD 0 P4D 0 Oops: 0000 [#1] SMP CPU: 4 PID: 209665 Comm: python3 Not tainted 6.1.0_for_upstream_min_debug_2022_12_12_17_02 #1 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:kmem_cache_alloc+0xcb/0x450 Code: ce 7e 49 8b 50 08 49 83 78 10 00 4d 8b 28 0f 84 cb 02 00 00 4d 85 ed 0f 84 c2 02 00 00 41 8b 44 24 28 48 8d 4a 01 49 8b 3c 24 <49> 8b 5c 05 00 4c 89 e8 65 48 0f c7 0f 0f 94 c0 84 c0 74 b8 41 8b RSP: 0018:ffff88822acbbab8 EFLAGS: 00010202 RAX: 0000000000000070 RBX: ffff8881c28e3e00 RCX: 00000000064f8dae RDX: 00000000064f8dad RSI: 0000000000000a20 RDI: 0000000000030d00 RBP: 0000000000000a20 R08: ffff8882f5d30d00 R09: ffff888104032f40 R10: ffff88810fade828 R11: 736f6d6570736575 R12: ffff88810081c000 R13: 00000000000002fb R14: ffffffff817fc865 R15: 0000000000000000 FS: 00007f9324ff9700(0000) GS:ffff8882f5d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000000000000036b CR3: 00000001125af004 CR4: 0000000000370ea0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> skb_clone+0x55/0xd0 ip6_finish_output2+0x3fe/0x690 ip6_finish_output+0xfa/0x310 ip6_send_skb+0x1e/0x60 udp_v6_send_skb+0x1e5/0x420 udpv6_sendmsg+0xb3c/0xe60 ? ip_mc_finish_output+0x180/0x180 ? __switch_to_asm+0x3a/0x60 ? __switch_to_asm+0x34/0x60 sock_sendmsg+0x33/0x40 __sys_sendto+0x103/0x160 ? _copy_to_user+0x21/0x30 ? kvm_clock_get_cycles+0xd/0x10 ? ktime_get_ts64+0x49/0xe0 __x64_sys_sendto+0x25/0x30 do_syscall_64+0x3d/0x90 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f9374f1ed14 Code: 42 41 f8 ff 44 8b 4c 24 2c 4c 8b 44 24 20 89 c5 44 8b 54 24 28 48 8b 54 24 18 b8 2c 00 00 00 48 8b 74 24 10 8b 7c 24 08 0f 05 <48> 3d 00 f0 ff ff 77 34 89 ef 48 89 44 24 08 e8 68 41 f8 ff 48 8b RSP: 002b:00007f9324ff7bd0 EFLAGS: 00000293 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007f9324ff7cc8 RCX: 00007f9374f1ed14 RDX: 00000000000002fb RSI: 00007f93000052f0 RDI: 0000000000000030 RBP: 0000000000000000 R08: 00007f9324ff7d40 R09: 000000000000001c R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 000000012a05f200 R14: 0000000000000001 R15: 00007f9374d57bdc </TASK>

In the Linux kernel, the following vulnerability has been resolved: scsi: lpfc: Fix null ndlp ptr dereference in abnormal exit path for GFT_ID An error case exit from lpfc_cmpl_ct_cmd_gft_id() results in a call to lpfc_nlp_put() with a null pointer to a nodelist structure. Changed lpfc_cmpl_ct_cmd_gft_id() to initialize nodelist pointer upon entry.

In the Linux kernel, the following vulnerability has been resolved: drm/bridge: megachips: Fix a null pointer dereference bug When removing the module we will get the following warning: [ 31.911505] i2c-core: driver [stdp2690-ge-b850v3-fw] unregistered [ 31.912484] general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN PTI [ 31.913338] KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] [ 31.915280] RIP: 0010:drm_bridge_remove+0x97/0x130 [ 31.921825] Call Trace: [ 31.922533] stdp4028_ge_b850v3_fw_remove+0x34/0x60 [megachips_stdpxxxx_ge_b850v3_fw] [ 31.923139] i2c_device_remove+0x181/0x1f0 The two bridges (stdp2690, stdp4028) do not probe at the same time, so the driver does not call ge_b850v3_resgiter() when probing, causing the driver to try to remove the object that has not been initialized. Fix this by checking whether both the bridges are probed.

In the Linux kernel, the following vulnerability has been resolved: mmc: rtsx_pci: fix return value check of mmc_add_host() mmc_add_host() may return error, if we ignore its return value, the memory that allocated in mmc_alloc_host() will be leaked and it will lead a kernel crash because of deleting not added device in the remove path. So fix this by checking the return value and calling mmc_free_host() in the error path, beside, runtime PM also needs be disabled.

In the Linux kernel, the following vulnerability has been resolved: drivers/md/md-bitmap: check the return value of md_bitmap_get_counter() Check the return value of md_bitmap_get_counter() in case it returns NULL pointer, which will result in a null pointer dereference. v2: update the check to include other dereference

In the Linux kernel, the following vulnerability has been resolved: RDMA/rxe: Fix BUG: KASAN: null-ptr-deref in rxe_qp_do_cleanup The function rxe_create_qp calls rxe_qp_from_init. If some error occurs, the error handler of function rxe_qp_from_init will set both scq and rcq to NULL. Then rxe_create_qp calls rxe_put to handle qp. In the end, rxe_qp_do_cleanup is called by rxe_put. rxe_qp_do_cleanup directly accesses scq and rcq before checking them. This will cause null-ptr-deref error. The call graph is as below: rxe_create_qp { ... rxe_qp_from_init { ... err1: ... qp->rcq = NULL; <---rcq is set to NULL qp->scq = NULL; <---scq is set to NULL ... } qp_init: rxe_put{ ... rxe_qp_do_cleanup { ... atomic_dec(&qp->scq->num_wq); <--- scq is accessed ... atomic_dec(&qp->rcq->num_wq); <--- rcq is accessed } }

In the Linux kernel, the following vulnerability has been resolved: gpiolib: cdev: fix NULL-pointer dereferences There are several places where we can crash the kernel by requesting lines, unbinding the GPIO device, then calling any of the system calls relevant to the GPIO character device's annonymous file descriptors: ioctl(), read(), poll(). While I observed it with the GPIO simulator, it will also happen for any of the GPIO devices that can be hot-unplugged - for instance any HID GPIO expander (e.g. CP2112). This affects both v1 and v2 uAPI. This fixes it partially by checking if gdev->chip is not NULL but it doesn't entirely remedy the situation as we still have a race condition in which another thread can remove the device after the check.

In the Linux kernel, the following vulnerability has been resolved: clk: zynq: Prevent null pointer dereference caused by kmalloc failure The kmalloc() in zynq_clk_setup() will return null if the physical memory has run out. As a result, if we use snprintf() to write data to the null address, the null pointer dereference bug will happen. This patch uses a stack variable to replace the kmalloc().

In the Linux kernel, the following vulnerability has been resolved: net: sched: cake: fix null pointer access issue when cake_init() fails When the default qdisc is cake, if the qdisc of dev_queue fails to be inited during mqprio_init(), cake_reset() is invoked to clear resources. In this case, the tins is NULL, and it will cause gpf issue. The process is as follows: qdisc_create_dflt() cake_init() q->tins = kvcalloc(...) --->failed, q->tins is NULL ... qdisc_put() ... cake_reset() ... cake_dequeue_one() b = &q->tins[...] --->q->tins is NULL The following is the Call Trace information: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:cake_dequeue_one+0xc9/0x3c0 Call Trace: <TASK> cake_reset+0xb1/0x140 qdisc_reset+0xed/0x6f0 qdisc_destroy+0x82/0x4c0 qdisc_put+0x9e/0xb0 qdisc_create_dflt+0x2c3/0x4a0 mqprio_init+0xa71/0x1760 qdisc_create+0x3eb/0x1000 tc_modify_qdisc+0x408/0x1720 rtnetlink_rcv_msg+0x38e/0xac0 netlink_rcv_skb+0x12d/0x3a0 netlink_unicast+0x4a2/0x740 netlink_sendmsg+0x826/0xcc0 sock_sendmsg+0xc5/0x100 ____sys_sendmsg+0x583/0x690 ___sys_sendmsg+0xe8/0x160 __sys_sendmsg+0xbf/0x160 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f89e5122d04 </TASK>

In the Linux kernel, the following vulnerability has been resolved: media: coda: Add check for dcoda_iram_alloc As the coda_iram_alloc may return NULL pointer, it should be better to check the return value in order to avoid NULL poineter dereference, same as the others.

In the Linux kernel, the following vulnerability has been resolved: fs: dlm: fix invalid derefence of sb_lvbptr I experience issues when putting a lkbsb on the stack and have sb_lvbptr field to a dangled pointer while not using DLM_LKF_VALBLK. It will crash with the following kernel message, the dangled pointer is here 0xdeadbeef as example: [ 102.749317] BUG: unable to handle page fault for address: 00000000deadbeef [ 102.749320] #PF: supervisor read access in kernel mode [ 102.749323] #PF: error_code(0x0000) - not-present page [ 102.749325] PGD 0 P4D 0 [ 102.749332] Oops: 0000 [#1] PREEMPT SMP PTI [ 102.749336] CPU: 0 PID: 1567 Comm: lock_torture_wr Tainted: G W 5.19.0-rc3+ #1565 [ 102.749343] Hardware name: Red Hat KVM/RHEL-AV, BIOS 1.16.0-2.module+el8.7.0+15506+033991b0 04/01/2014 [ 102.749344] RIP: 0010:memcpy_erms+0x6/0x10 [ 102.749353] Code: cc cc cc cc eb 1e 0f 1f 00 48 89 f8 48 89 d1 48 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8 48 89 d1 <f3> a4 c3 0f 1f 80 00 00 00 00 48 89 f8 48 83 fa 20 72 7e 40 38 fe [ 102.749355] RSP: 0018:ffff97a58145fd08 EFLAGS: 00010202 [ 102.749358] RAX: ffff901778b77070 RBX: 0000000000000000 RCX: 0000000000000040 [ 102.749360] RDX: 0000000000000040 RSI: 00000000deadbeef RDI: ffff901778b77070 [ 102.749362] RBP: ffff97a58145fd10 R08: ffff901760b67a70 R09: 0000000000000001 [ 102.749364] R10: ffff9017008e2cb8 R11: 0000000000000001 R12: ffff901760b67a70 [ 102.749366] R13: ffff901760b78f00 R14: 0000000000000003 R15: 0000000000000001 [ 102.749368] FS: 0000000000000000(0000) GS:ffff901876e00000(0000) knlGS:0000000000000000 [ 102.749372] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 102.749374] CR2: 00000000deadbeef CR3: 000000017c49a004 CR4: 0000000000770ef0 [ 102.749376] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 102.749378] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 102.749379] PKRU: 55555554 [ 102.749381] Call Trace: [ 102.749382] <TASK> [ 102.749383] ? send_args+0xb2/0xd0 [ 102.749389] send_common+0xb7/0xd0 [ 102.749395] _unlock_lock+0x2c/0x90 [ 102.749400] unlock_lock.isra.56+0x62/0xa0 [ 102.749405] dlm_unlock+0x21e/0x330 [ 102.749411] ? lock_torture_stats+0x80/0x80 [dlm_locktorture] [ 102.749416] torture_unlock+0x5a/0x90 [dlm_locktorture] [ 102.749419] ? preempt_count_sub+0xba/0x100 [ 102.749427] lock_torture_writer+0xbd/0x150 [dlm_locktorture] [ 102.786186] kthread+0x10a/0x130 [ 102.786581] ? kthread_complete_and_exit+0x20/0x20 [ 102.787156] ret_from_fork+0x22/0x30 [ 102.787588] </TASK> [ 102.787855] Modules linked in: dlm_locktorture torture rpcsec_gss_krb5 intel_rapl_msr intel_rapl_common kvm_intel iTCO_wdt iTCO_vendor_support kvm vmw_vsock_virtio_transport qxl irqbypass vmw_vsock_virtio_transport_common drm_ttm_helper crc32_pclmul joydev crc32c_intel ttm vsock virtio_scsi virtio_balloon snd_pcm drm_kms_helper virtio_console snd_timer snd drm soundcore syscopyarea i2c_i801 sysfillrect sysimgblt i2c_smbus pcspkr fb_sys_fops lpc_ich serio_raw [ 102.792536] CR2: 00000000deadbeef [ 102.792930] ---[ end trace 0000000000000000 ]--- This patch fixes the issue by checking also on DLM_LKF_VALBLK on exflags is set when copying the lvbptr array instead of if it's just null which fixes for me the issue. I think this patch can fix other dlm users as well, depending how they handle the init, freeing memory handling of sb_lvbptr and don't set DLM_LKF_VALBLK for some dlm_lock() calls. It might a there could be a hidden issue all the time. However with checking on DLM_LKF_VALBLK the user always need to provide a sb_lvbptr non-null value. There might be more intelligent handling between per ls lvblen, DLM_LKF_VALBLK and non-null to report the user the way how DLM API is used is wrong but can be added for later, this will only fix the current behaviour.

In the Linux kernel, the following vulnerability has been resolved: dm: call the resume method on internal suspend There is this reported crash when experimenting with the lvm2 testsuite. The list corruption is caused by the fact that the postsuspend and resume methods were not paired correctly; there were two consecutive calls to the origin_postsuspend function. The second call attempts to remove the "hash_list" entry from a list, while it was already removed by the first call. Fix __dm_internal_resume so that it calls the preresume and resume methods of the table's targets. If a preresume method of some target fails, we are in a tricky situation. We can't return an error because dm_internal_resume isn't supposed to return errors. We can't return success, because then the "resume" and "postsuspend" methods would not be paired correctly. So, we set the DMF_SUSPENDED flag and we fake normal suspend - it may confuse userspace tools, but it won't cause a kernel crash. ------------[ cut here ]------------ kernel BUG at lib/list_debug.c:56! invalid opcode: 0000 [#1] PREEMPT SMP CPU: 1 PID: 8343 Comm: dmsetup Not tainted 6.8.0-rc6 #4 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 RIP: 0010:__list_del_entry_valid_or_report+0x77/0xc0 <snip> RSP: 0018:ffff8881b831bcc0 EFLAGS: 00010282 RAX: 000000000000004e RBX: ffff888143b6eb80 RCX: 0000000000000000 RDX: 0000000000000001 RSI: ffffffff819053d0 RDI: 00000000ffffffff RBP: ffff8881b83a3400 R08: 00000000fffeffff R09: 0000000000000058 R10: 0000000000000000 R11: ffffffff81a24080 R12: 0000000000000001 R13: ffff88814538e000 R14: ffff888143bc6dc0 R15: ffffffffa02e4bb0 FS: 00000000f7c0f780(0000) GS:ffff8893f0a40000(0000) knlGS:0000000000000000 CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 CR2: 0000000057fb5000 CR3: 0000000143474000 CR4: 00000000000006b0 Call Trace: <TASK> ? die+0x2d/0x80 ? do_trap+0xeb/0xf0 ? __list_del_entry_valid_or_report+0x77/0xc0 ? do_error_trap+0x60/0x80 ? __list_del_entry_valid_or_report+0x77/0xc0 ? exc_invalid_op+0x49/0x60 ? __list_del_entry_valid_or_report+0x77/0xc0 ? asm_exc_invalid_op+0x16/0x20 ? table_deps+0x1b0/0x1b0 [dm_mod] ? __list_del_entry_valid_or_report+0x77/0xc0 origin_postsuspend+0x1a/0x50 [dm_snapshot] dm_table_postsuspend_targets+0x34/0x50 [dm_mod] dm_suspend+0xd8/0xf0 [dm_mod] dev_suspend+0x1f2/0x2f0 [dm_mod] ? table_deps+0x1b0/0x1b0 [dm_mod] ctl_ioctl+0x300/0x5f0 [dm_mod] dm_compat_ctl_ioctl+0x7/0x10 [dm_mod] __x64_compat_sys_ioctl+0x104/0x170 do_syscall_64+0x184/0x1b0 entry_SYSCALL_64_after_hwframe+0x46/0x4e RIP: 0033:0xf7e6aead <snip> ---[ end trace 0000000000000000 ]---

In the Linux kernel, the following vulnerability has been resolved: soundwire: revisit driver bind/unbind and callbacks In the SoundWire probe, we store a pointer from the driver ops into the 'slave' structure. This can lead to kernel oopses when unbinding codec drivers, e.g. with the following sequence to remove machine driver and codec driver. /sbin/modprobe -r snd_soc_sof_sdw /sbin/modprobe -r snd_soc_rt711 The full details can be found in the BugLink below, for reference the two following examples show different cases of driver ops/callbacks being invoked after the driver .remove(). kernel: BUG: kernel NULL pointer dereference, address: 0000000000000150 kernel: Workqueue: events cdns_update_slave_status_work [soundwire_cadence] kernel: RIP: 0010:mutex_lock+0x19/0x30 kernel: Call Trace: kernel: ? sdw_handle_slave_status+0x426/0xe00 [soundwire_bus 94ff184bf398570c3f8ff7efe9e32529f532e4ae] kernel: ? newidle_balance+0x26a/0x400 kernel: ? cdns_update_slave_status_work+0x1e9/0x200 [soundwire_cadence 1bcf98eebe5ba9833cd433323769ac923c9c6f82] kernel: BUG: unable to handle page fault for address: ffffffffc07654c8 kernel: Workqueue: pm pm_runtime_work kernel: RIP: 0010:sdw_bus_prep_clk_stop+0x6f/0x160 [soundwire_bus] kernel: Call Trace: kernel: <TASK> kernel: sdw_cdns_clock_stop+0xb5/0x1b0 [soundwire_cadence 1bcf98eebe5ba9833cd433323769ac923c9c6f82] kernel: intel_suspend_runtime+0x5f/0x120 [soundwire_intel aca858f7c87048d3152a4a41bb68abb9b663a1dd] kernel: ? dpm_sysfs_remove+0x60/0x60 This was not detected earlier in Intel tests since the tests first remove the parent PCI device and shut down the bus. The sequence above is a corner case which keeps the bus operational but without a driver bound. While trying to solve this kernel oopses, it became clear that the existing SoundWire bus does not deal well with the unbind case. Commit 528be501b7d4a ("soundwire: sdw_slave: add probe_complete structure and new fields") added a 'probed' status variable and a 'probe_complete' struct completion. This status is however not reset on remove and likewise the 'probe complete' is not re-initialized, so the bind/unbind/bind test cases would fail. The timeout used before the 'update_status' callback was also a bad idea in hindsight, there should really be no timing assumption as to if and when a driver is bound to a device. An initial draft was based on device_lock() and device_unlock() was tested. This proved too complicated, with deadlocks created during the suspend-resume sequences, which also use the same device_lock/unlock() as the bind/unbind sequences. On a CometLake device, a bad DSDT/BIOS caused spurious resumes and the use of device_lock() caused hangs during suspend. After multiple weeks or testing and painful reverse-engineering of deadlocks on different devices, we looked for alternatives that did not interfere with the device core. A bus notifier was used successfully to keep track of DRIVER_BOUND and DRIVER_UNBIND events. This solved the bind-unbind-bind case in tests, but it can still be defeated with a theoretical corner case where the memory is freed by a .remove while the callback is in use. The notifier only helps make sure the driver callbacks are valid, but not that the memory allocated in probe remains valid while the callbacks are invoked. This patch suggests the introduction of a new 'sdw_dev_lock' mutex protecting probe/remove and all driver callbacks. Since this mutex is 'local' to SoundWire only, it does not interfere with existing locks and does not create deadlocks. In addition, this patch removes the 'probe_complete' completion, instead we directly invoke the 'update_status' from the probe routine. That removes any sort of timing dependency and a much better support for the device/driver model, the driver could be bound before the bus started, or eons after the bus started and the hardware would be properly initialized in all cases. BugLink: https://github.com/thesofproject/linux/is ---truncated---

In the Linux kernel, the following vulnerability has been resolved: mlxsw: spectrum_acl_tcam: Fix NULL pointer dereference in error path When calling mlxsw_sp_acl_tcam_region_destroy() from an error path after failing to attach the region to an ACL group, we hit a NULL pointer dereference upon 'region->group->tcam' [1]. Fix by retrieving the 'tcam' pointer using mlxsw_sp_acl_to_tcam(). [1] BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] RIP: 0010:mlxsw_sp_acl_tcam_region_destroy+0xa0/0xd0 [...] Call Trace: mlxsw_sp_acl_tcam_vchunk_get+0x88b/0xa20 mlxsw_sp_acl_tcam_ventry_add+0x25/0xe0 mlxsw_sp_acl_rule_add+0x47/0x240 mlxsw_sp_flower_replace+0x1a9/0x1d0 tc_setup_cb_add+0xdc/0x1c0 fl_hw_replace_filter+0x146/0x1f0 fl_change+0xc17/0x1360 tc_new_tfilter+0x472/0xb90 rtnetlink_rcv_msg+0x313/0x3b0 netlink_rcv_skb+0x58/0x100 netlink_unicast+0x244/0x390 netlink_sendmsg+0x1e4/0x440 ____sys_sendmsg+0x164/0x260 ___sys_sendmsg+0x9a/0xe0 __sys_sendmsg+0x7a/0xc0 do_syscall_64+0x40/0xe0 entry_SYSCALL_64_after_hwframe+0x63/0x6b

In the Linux kernel, the following vulnerability has been resolved: pnode: terminate at peers of source The propagate_mnt() function handles mount propagation when creating mounts and propagates the source mount tree @source_mnt to all applicable nodes of the destination propagation mount tree headed by @dest_mnt. Unfortunately it contains a bug where it fails to terminate at peers of @source_mnt when looking up copies of the source mount that become masters for copies of the source mount tree mounted on top of slaves in the destination propagation tree causing a NULL dereference. Once the mechanics of the bug are understood it's easy to trigger. Because of unprivileged user namespaces it is available to unprivileged users. While fixing this bug we've gotten confused multiple times due to unclear terminology or missing concepts. So let's start this with some clarifications: * The terms "master" or "peer" denote a shared mount. A shared mount belongs to a peer group. * A peer group is a set of shared mounts that propagate to each other. They are identified by a peer group id. The peer group id is available in @shared_mnt->mnt_group_id. Shared mounts within the same peer group have the same peer group id. The peers in a peer group can be reached via @shared_mnt->mnt_share. * The terms "slave mount" or "dependent mount" denote a mount that receives propagation from a peer in a peer group. IOW, shared mounts may have slave mounts and slave mounts have shared mounts as their master. Slave mounts of a given peer in a peer group are listed on that peers slave list available at @shared_mnt->mnt_slave_list. * The term "master mount" denotes a mount in a peer group. IOW, it denotes a shared mount or a peer mount in a peer group. The term "master mount" - or "master" for short - is mostly used when talking in the context of slave mounts that receive propagation from a master mount. A master mount of a slave identifies the closest peer group a slave mount receives propagation from. The master mount of a slave can be identified via @slave_mount->mnt_master. Different slaves may point to different masters in the same peer group. * Multiple peers in a peer group can have non-empty ->mnt_slave_lists. Non-empty ->mnt_slave_lists of peers don't intersect. Consequently, to ensure all slave mounts of a peer group are visited the ->mnt_slave_lists of all peers in a peer group have to be walked. * Slave mounts point to a peer in the closest peer group they receive propagation from via @slave_mnt->mnt_master (see above). Together with these peers they form a propagation group (see below). The closest peer group can thus be identified through the peer group id @slave_mnt->mnt_master->mnt_group_id of the peer/master that a slave mount receives propagation from. * A shared-slave mount is a slave mount to a peer group pg1 while also a peer in another peer group pg2. IOW, a peer group may receive propagation from another peer group. If a peer group pg1 is a slave to another peer group pg2 then all peers in peer group pg1 point to the same peer in peer group pg2 via ->mnt_master. IOW, all peers in peer group pg1 appear on the same ->mnt_slave_list. IOW, they cannot be slaves to different peer groups. * A pure slave mount is a slave mount that is a slave to a peer group but is not a peer in another peer group. * A propagation group denotes the set of mounts consisting of a single peer group pg1 and all slave mounts and shared-slave mounts that point to a peer in that peer group via ->mnt_master. IOW, all slave mounts such that @slave_mnt->mnt_master->mnt_group_id is equal to @shared_mnt->mnt_group_id. The concept of a propagation group makes it easier to talk about a single propagation level in a propagation tree. For example, in propagate_mnt() the immediate peers of @dest_mnt and all slaves of @dest_mnt's peer group form a propagation group pr ---truncated---

In the Linux kernel, the following vulnerability has been resolved: mtd: lpddr2_nvm: Fix possible null-ptr-deref It will cause null-ptr-deref when resource_size(add_range) invoked, if platform_get_resource() returns NULL.

In the Linux kernel, the following vulnerability has been resolved: media: dvb-usb: az6027: fix null-ptr-deref in az6027_i2c_xfer() Wei Chen reports a kernel bug as blew: general protection fault, probably for non-canonical address KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017] ... Call Trace: <TASK> __i2c_transfer+0x77e/0x1930 drivers/i2c/i2c-core-base.c:2109 i2c_transfer+0x1d5/0x3d0 drivers/i2c/i2c-core-base.c:2170 i2cdev_ioctl_rdwr+0x393/0x660 drivers/i2c/i2c-dev.c:297 i2cdev_ioctl+0x75d/0x9f0 drivers/i2c/i2c-dev.c:458 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fd834a8bded In az6027_i2c_xfer(), if msg[i].addr is 0x99, a null-ptr-deref will caused when accessing msg[i].buf. For msg[i].len is 0 and msg[i].buf is null. Fix this by checking msg[i].len in az6027_i2c_xfer().

In the Linux kernel, the following vulnerability has been resolved: parisc: led: Fix potential null-ptr-deref in start_task() start_task() calls create_singlethread_workqueue() and not checked the ret value, which may return NULL. And a null-ptr-deref may happen: start_task() create_singlethread_workqueue() # failed, led_wq is NULL queue_delayed_work() queue_delayed_work_on() __queue_delayed_work() # warning here, but continue __queue_work() # access wq->flags, null-ptr-deref Check the ret value and return -ENOMEM if it is NULL.

In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu/pm: Fix NULL pointer dereference when get power limit Because powerplay_table initialization is skipped under sriov case, We check and set default lower and upper OD value if powerplay_table is NULL.

In the Linux kernel, the following vulnerability has been resolved: locking/csd_lock: Change csdlock_debug from early_param to __setup The csdlock_debug kernel-boot parameter is parsed by the early_param() function csdlock_debug(). If set, csdlock_debug() invokes static_branch_enable() to enable csd_lock_wait feature, which triggers a panic on arm64 for kernels built with CONFIG_SPARSEMEM=y and CONFIG_SPARSEMEM_VMEMMAP=n. With CONFIG_SPARSEMEM_VMEMMAP=n, __nr_to_section is called in static_key_enable() and returns NULL, resulting in a NULL dereference because mem_section is initialized only later in sparse_init(). This is also a problem for powerpc because early_param() functions are invoked earlier than jump_label_init(), also resulting in static_key_enable() failures. These failures cause the warning "static key 'xxx' used before call to jump_label_init()". Thus, early_param is too early for csd_lock_wait to run static_branch_enable(), so changes it to __setup to fix these.

In the Linux kernel, the following vulnerability has been resolved: iio: light: isl29028: Fix the warning in isl29028_remove() The driver use the non-managed form of the register function in isl29028_remove(). To keep the release order as mirroring the ordering in probe, the driver should use non-managed form in probe, too. The following log reveals it: [ 32.374955] isl29028 0-0010: remove [ 32.376861] general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN PTI [ 32.377676] KASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037] [ 32.379432] RIP: 0010:kernfs_find_and_get_ns+0x28/0xe0 [ 32.385461] Call Trace: [ 32.385807] sysfs_unmerge_group+0x59/0x110 [ 32.386110] dpm_sysfs_remove+0x58/0xc0 [ 32.386391] device_del+0x296/0xe50 [ 32.386959] cdev_device_del+0x1d/0xd0 [ 32.387231] devm_iio_device_unreg+0x27/0xb0 [ 32.387542] devres_release_group+0x319/0x3d0 [ 32.388162] i2c_device_remove+0x93/0x1f0

In the Linux kernel, the following vulnerability has been resolved: nfp: flower: handle acti_netdevs allocation failure The kmalloc_array() in nfp_fl_lag_do_work() will return null, if the physical memory has run out. As a result, if we dereference the acti_netdevs, the null pointer dereference bugs will happen. This patch adds a check to judge whether allocation failure occurs. If it happens, the delayed work will be rescheduled and try again.

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: mlme: fix null-ptr deref on failed assoc If association to an AP without a link 0 fails, then we crash in tracing because it assumes that either ap_mld_addr or link 0 BSS is valid, since we clear sdata->vif.valid_links and then don't add the ap_mld_addr to the struct. Since we clear also sdata->vif.cfg.ap_addr, keep a local copy of it and assign it earlier, before clearing valid_links, to fix this.

In the Linux kernel, the following vulnerability has been resolved: mmc: wmt-sdmmc: fix return value check of mmc_add_host() mmc_add_host() may return error, if we ignore its return value, the memory that allocated in mmc_alloc_host() will be leaked and it will lead a kernel crash because of deleting not added device in the remove path. So fix this by checking the return value and goto error path which will call mmc_free_host(), besides, clk_disable_unprepare() also needs be called.

In the Linux kernel, the following vulnerability has been resolved: scsi: iscsi: iscsi_tcp: Fix null-ptr-deref while calling getpeername() Fix a NULL pointer crash that occurs when we are freeing the socket at the same time we access it via sysfs. The problem is that: 1. iscsi_sw_tcp_conn_get_param() and iscsi_sw_tcp_host_get_param() take the frwd_lock and do sock_hold() then drop the frwd_lock. sock_hold() does a get on the "struct sock". 2. iscsi_sw_tcp_release_conn() does sockfd_put() which does the last put on the "struct socket" and that does __sock_release() which sets the sock->ops to NULL. 3. iscsi_sw_tcp_conn_get_param() and iscsi_sw_tcp_host_get_param() then call kernel_getpeername() which accesses the NULL sock->ops. Above we do a get on the "struct sock", but we needed a get on the "struct socket". Originally, we just held the frwd_lock the entire time but in commit bcf3a2953d36 ("scsi: iscsi: iscsi_tcp: Avoid holding spinlock while calling getpeername()") we switched to refcount based because the network layer changed and started taking a mutex in that path, so we could no longer hold the frwd_lock. Instead of trying to maintain multiple refcounts, this just has us use a mutex for accessing the socket in the interface code paths.

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Fix potential null-deref in dm_resume [Why] Fixing smatch error: dm_resume() error: we previously assumed 'aconnector->dc_link' could be null [How] Check if dc_link null at the beginning of the loop, so further checks can be dropped.