The em_syscall function in arch/x86/kvm/emulate.c in the KVM implementation in the Linux kernel before 3.2.14 does not properly handle the 0f05 (aka syscall) opcode, which allows guest OS users to cause a denial of service (guest OS crash) via a crafted application, as demonstrated by an NASM file.

In the Linux kernel, the following vulnerability has been resolved: tcp: Fix data-races around sysctl_tcp_base_mss. While reading sysctl_tcp_base_mss, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers.

The load_elf_binary function in fs/binfmt_elf.c in the Linux kernel before 2.6.32.8 on the x86_64 platform does not ensure that the ELF interpreter is available before a call to the SET_PERSONALITY macro, which allows local users to cause a denial of service (system crash) via a 32-bit application that attempts to execute a 64-bit application and then triggers a segmentation fault, as demonstrated by amd64_killer, related to the flush_old_exec function.

In the Linux kernel, the following vulnerability has been resolved: ice: fix concurrent reset and removal of VFs Commit c503e63200c6 ("ice: Stop processing VF messages during teardown") introduced a driver state flag, ICE_VF_DEINIT_IN_PROGRESS, which is intended to prevent some issues with concurrently handling messages from VFs while tearing down the VFs. This change was motivated by crashes caused while tearing down and bringing up VFs in rapid succession. It turns out that the fix actually introduces issues with the VF driver caused because the PF no longer responds to any messages sent by the VF during its .remove routine. This results in the VF potentially removing its DMA memory before the PF has shut down the device queues. Additionally, the fix doesn't actually resolve concurrency issues within the ice driver. It is possible for a VF to initiate a reset just prior to the ice driver removing VFs. This can result in the remove task concurrently operating while the VF is being reset. This results in similar memory corruption and panics purportedly fixed by that commit. Fix this concurrency at its root by protecting both the reset and removal flows using the existing VF cfg_lock. This ensures that we cannot remove the VF while any outstanding critical tasks such as a virtchnl message or a reset are occurring. This locking change also fixes the root cause originally fixed by commit c503e63200c6 ("ice: Stop processing VF messages during teardown"), so we can simply revert it. Note that I kept these two changes together because simply reverting the original commit alone would leave the driver vulnerable to worse race conditions.

A flaw was found in the MCTP protocol in the Linux kernel. The function mctp_unregister() reclaims the device's relevant resource when a netcard detaches. However, a running routine may be unaware of this and cause the use-after-free of the mdev->addrs object, potentially leading to a denial of service.

IBM Spectrum Protect 8.1.0.0 through 8.1.17.0 could allow a local user to cause a denial of service due to due to improper time-of-check to time-of-use functionality. IBM X-Force ID: 256012.

The agp subsystem in the Linux kernel 2.6.38.5 and earlier does not properly restrict memory allocation by the (1) AGPIOC_RESERVE and (2) AGPIOC_ALLOCATE ioctls, which allows local users to cause a denial of service (memory consumption) by making many calls to these ioctls.

The br_multicast_add_group function in net/bridge/br_multicast.c in the Linux kernel before 2.6.38, when a certain Ethernet bridge configuration is used, allows local users to cause a denial of service (memory corruption and system crash) by sending IGMP packets to a local interface.

Double free vulnerability in the inotify subsystem in the Linux kernel before 2.6.39 allows local users to cause a denial of service (system crash) via vectors involving failed attempts to create files. NOTE: this vulnerability exists because of an incorrect fix for CVE-2010-4250.

The blk_rq_map_user_iov function in block/blk-map.c in the Linux kernel before 2.6.37-rc7 allows local users to cause a denial of service (panic) via a zero-length I/O request in a device ioctl to a SCSI device, related to an unaligned map. NOTE: this vulnerability exists because of an incomplete fix for CVE-2010-4163.

The blk_rq_map_user_iov function in block/blk-map.c in the Linux kernel before 2.6.36.2 allows local users to cause a denial of service (panic) via a zero-length I/O request in a device ioctl to a SCSI device.

Multiple integer overflows in fs/bio.c in the Linux kernel before 2.6.36.2 allow local users to cause a denial of service (system crash) via a crafted device ioctl to a SCSI device.

Integer overflow in the ext4_ext_get_blocks function in fs/ext4/extents.c in the Linux kernel before 2.6.34 allows local users to cause a denial of service (BUG and system crash) via a write operation on the last block of a large file, followed by a sync operation.

Multiple integer overflows in the snd_ctl_new function in sound/core/control.c in the Linux kernel before 2.6.36-rc5-next-20100929 allow local users to cause a denial of service (heap memory corruption) or possibly have unspecified other impact via a crafted (1) SNDRV_CTL_IOCTL_ELEM_ADD or (2) SNDRV_CTL_IOCTL_ELEM_REPLACE ioctl call.

In the Linux kernel, the following vulnerability has been resolved: btrfs: qgroup: do not warn on record without old_roots populated [BUG] There are some reports from the mailing list that since v6.1 kernel, the WARN_ON() inside btrfs_qgroup_account_extent() gets triggered during rescan: WARNING: CPU: 3 PID: 6424 at fs/btrfs/qgroup.c:2756 btrfs_qgroup_account_extents+0x1ae/0x260 [btrfs] CPU: 3 PID: 6424 Comm: snapperd Tainted: P OE 6.1.2-1-default #1 openSUSE Tumbleweed 05c7a1b1b61d5627475528f71f50444637b5aad7 RIP: 0010:btrfs_qgroup_account_extents+0x1ae/0x260 [btrfs] Call Trace: <TASK> btrfs_commit_transaction+0x30c/0xb40 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6] ? start_transaction+0xc3/0x5b0 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6] btrfs_qgroup_rescan+0x42/0xc0 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6] btrfs_ioctl+0x1ab9/0x25c0 [btrfs c39c9c546c241c593f03bd6d5f39ea1b676250f6] ? __rseq_handle_notify_resume+0xa9/0x4a0 ? mntput_no_expire+0x4a/0x240 ? __seccomp_filter+0x319/0x4d0 __x64_sys_ioctl+0x90/0xd0 do_syscall_64+0x5b/0x80 ? syscall_exit_to_user_mode+0x17/0x40 ? do_syscall_64+0x67/0x80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fd9b790d9bf </TASK> [CAUSE] Since commit e15e9f43c7ca ("btrfs: introduce BTRFS_QGROUP_RUNTIME_FLAG_NO_ACCOUNTING to skip qgroup accounting"), if our qgroup is already in inconsistent state, we will no longer do the time-consuming backref walk. This can leave some qgroup records without a valid old_roots ulist. Normally this is fine, as btrfs_qgroup_account_extents() would also skip those records if we have NO_ACCOUNTING flag set. But there is a small window, if we have NO_ACCOUNTING flag set, and inserted some qgroup_record without a old_roots ulist, but then the user triggered a qgroup rescan. During btrfs_qgroup_rescan(), we firstly clear NO_ACCOUNTING flag, then commit current transaction. And since we have a qgroup_record with old_roots = NULL, we trigger the WARN_ON() during btrfs_qgroup_account_extents(). [FIX] Unfortunately due to the introduction of NO_ACCOUNTING flag, the assumption that every qgroup_record would have its old_roots populated is no longer correct. Fix the false alerts and drop the WARN_ON().

The Linux kernel 2.6.9 through 2.6.17 on the x86_64 and amd64 platforms allows local users to cause a denial of service (panic) via a 32-bit application that calls mprotect on its Virtual Dynamic Shared Object (VDSO) page and then triggers a segmentation fault.

In the Linux kernel, the following vulnerability has been resolved: irqchip/gic-v4: Don't allow a VMOVP on a dying VPE Kunkun Jiang reported that there is a small window of opportunity for userspace to force a change of affinity for a VPE while the VPE has already been unmapped, but the corresponding doorbell interrupt still visible in /proc/irq/. Plug the race by checking the value of vmapp_count, which tracks whether the VPE is mapped ot not, and returning an error in this case. This involves making vmapp_count common to both GICv4.1 and its v4.0 ancestor.

drivers/firewire/ohci.c in the Linux kernel before 2.6.32-git9, when packet-per-buffer mode is used, allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unknown other impact via an unspecified ioctl associated with receiving an ISO packet that contains zero in the payload-length field.

A vulnerability was found in Linux kernel, where a use-after-frees in nouveau's postclose() handler could happen if removing device (that is not common to remove video card physically without power-off, but same happens if "unbind" the driver).

In the Linux kernel, the following vulnerability has been resolved: btrfs: use latest_dev in btrfs_show_devname The test case btrfs/238 reports the warning below: WARNING: CPU: 3 PID: 481 at fs/btrfs/super.c:2509 btrfs_show_devname+0x104/0x1e8 [btrfs] CPU: 2 PID: 1 Comm: systemd Tainted: G W O 5.14.0-rc1-custom #72 Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015 Call trace: btrfs_show_devname+0x108/0x1b4 [btrfs] show_mountinfo+0x234/0x2c4 m_show+0x28/0x34 seq_read_iter+0x12c/0x3c4 vfs_read+0x29c/0x2c8 ksys_read+0x80/0xec __arm64_sys_read+0x28/0x34 invoke_syscall+0x50/0xf8 do_el0_svc+0x88/0x138 el0_svc+0x2c/0x8c el0t_64_sync_handler+0x84/0xe4 el0t_64_sync+0x198/0x19c Reason: While btrfs_prepare_sprout() moves the fs_devices::devices into fs_devices::seed_list, the btrfs_show_devname() searches for the devices and found none, leading to the warning as in above. Fix: latest_dev is updated according to the changes to the device list. That means we could use the latest_dev->name to show the device name in /proc/self/mounts, the pointer will be always valid as it's assigned before the device is deleted from the list in remove or replace. The RCU protection is sufficient as the device structure is freed after synchronization.

In the Linux kernel, the following vulnerability has been resolved: s390/qeth: fix deadlock during failing recovery Commit 0b9902c1fcc5 ("s390/qeth: fix deadlock during recovery") removed taking discipline_mutex inside qeth_do_reset(), fixing potential deadlocks. An error path was missed though, that still takes discipline_mutex and thus has the original deadlock potential. Intermittent deadlocks were seen when a qeth channel path is configured offline, causing a race between qeth_do_reset and ccwgroup_remove. Call qeth_set_offline() directly in the qeth_do_reset() error case and then a new variant of ccwgroup_set_offline(), without taking discipline_mutex.

An issue was discovered in the Linux kernel before 5.15.11. There is a memory leak in the __rds_conn_create() function in net/rds/connection.c in a certain combination of circumstances.

The md driver (drivers/md/md.c) in the Linux kernel before 2.6.30.2 might allow local users to cause a denial of service (NULL pointer dereference) via vectors related to "suspend_* sysfs attributes" and the (1) suspend_lo_store or (2) suspend_hi_store functions. NOTE: this is only a vulnerability when sysfs is writable by an attacker.

Race condition in the store_int_with_restart() function in arch/x86/kernel/cpu/mcheck/mce.c in the Linux kernel through 4.15.7 allows local users to cause a denial of service (panic) by leveraging root access to write to the check_interval file in a /sys/devices/system/machinecheck/machinecheck<cpu number> directory. NOTE: a third party has indicated that this report is not security relevant

The inode double locking code in fs/ocfs2/file.c in the Linux kernel 2.6.30 before 2.6.30-rc3, 2.6.27 before 2.6.27.24, 2.6.29 before 2.6.29.4, and possibly other versions down to 2.6.19 allows local users to cause a denial of service (prevention of file creation and removal) via a series of splice system calls that trigger a deadlock between the generic_file_splice_write, splice_from_pipe, and ocfs2_file_splice_write functions.

A denial of service vulnerability was reported in some ThinkPad models that could cause a system to crash when the Enhanced Biometrics setting is enabled in BIOS.

The console selection feature in the Linux kernel 2.6.28 before 2.6.28.4, 2.6.25, and possibly earlier versions, when the UTF-8 console is used, allows physically proximate attackers to cause a denial of service (memory corruption) by selecting a small number of 3-byte UTF-8 characters, which triggers an "off-by-two memory error." NOTE: it is not clear whether this issue crosses privilege boundaries.

In the Linux kernel, the following vulnerability has been resolved: wireguard: receive: annotate data-race around receiving_counter.counter Syzkaller with KCSAN identified a data-race issue when accessing keypair->receiving_counter.counter. Use READ_ONCE() and WRITE_ONCE() annotations to mark the data race as intentional. BUG: KCSAN: data-race in wg_packet_decrypt_worker / wg_packet_rx_poll write to 0xffff888107765888 of 8 bytes by interrupt on cpu 0: counter_validate drivers/net/wireguard/receive.c:321 [inline] wg_packet_rx_poll+0x3ac/0xf00 drivers/net/wireguard/receive.c:461 __napi_poll+0x60/0x3b0 net/core/dev.c:6536 napi_poll net/core/dev.c:6605 [inline] net_rx_action+0x32b/0x750 net/core/dev.c:6738 __do_softirq+0xc4/0x279 kernel/softirq.c:553 do_softirq+0x5e/0x90 kernel/softirq.c:454 __local_bh_enable_ip+0x64/0x70 kernel/softirq.c:381 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:167 [inline] _raw_spin_unlock_bh+0x36/0x40 kernel/locking/spinlock.c:210 spin_unlock_bh include/linux/spinlock.h:396 [inline] ptr_ring_consume_bh include/linux/ptr_ring.h:367 [inline] wg_packet_decrypt_worker+0x6c5/0x700 drivers/net/wireguard/receive.c:499 process_one_work kernel/workqueue.c:2633 [inline] ... read to 0xffff888107765888 of 8 bytes by task 3196 on cpu 1: decrypt_packet drivers/net/wireguard/receive.c:252 [inline] wg_packet_decrypt_worker+0x220/0x700 drivers/net/wireguard/receive.c:501 process_one_work kernel/workqueue.c:2633 [inline] process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2706 worker_thread+0x525/0x730 kernel/workqueue.c:2787 ...

In the Linux kernel, the following vulnerability has been resolved: hv_netvsc: Fix race condition between netvsc_probe and netvsc_remove In commit ac5047671758 ("hv_netvsc: Disable NAPI before closing the VMBus channel"), napi_disable was getting called for all channels, including all subchannels without confirming if they are enabled or not. This caused hv_netvsc getting hung at napi_disable, when netvsc_probe() has finished running but nvdev->subchan_work has not started yet. netvsc_subchan_work() -> rndis_set_subchannel() has not created the sub-channels and because of that netvsc_sc_open() is not running. netvsc_remove() calls cancel_work_sync(&nvdev->subchan_work), for which netvsc_subchan_work did not run. netif_napi_add() sets the bit NAPI_STATE_SCHED because it ensures NAPI cannot be scheduled. Then netvsc_sc_open() -> napi_enable will clear the NAPIF_STATE_SCHED bit, so it can be scheduled. napi_disable() does the opposite. Now during netvsc_device_remove(), when napi_disable is called for those subchannels, napi_disable gets stuck on infinite msleep. This fix addresses this problem by ensuring that napi_disable() is not getting called for non-enabled NAPI struct. But netif_napi_del() is still necessary for these non-enabled NAPI struct for cleanup purpose. Call trace: [ 654.559417] task:modprobe state:D stack: 0 pid: 2321 ppid: 1091 flags:0x00004002 [ 654.568030] Call Trace: [ 654.571221] <TASK> [ 654.573790] __schedule+0x2d6/0x960 [ 654.577733] schedule+0x69/0xf0 [ 654.581214] schedule_timeout+0x87/0x140 [ 654.585463] ? __bpf_trace_tick_stop+0x20/0x20 [ 654.590291] msleep+0x2d/0x40 [ 654.593625] napi_disable+0x2b/0x80 [ 654.597437] netvsc_device_remove+0x8a/0x1f0 [hv_netvsc] [ 654.603935] rndis_filter_device_remove+0x194/0x1c0 [hv_netvsc] [ 654.611101] ? do_wait_intr+0xb0/0xb0 [ 654.615753] netvsc_remove+0x7c/0x120 [hv_netvsc] [ 654.621675] vmbus_remove+0x27/0x40 [hv_vmbus]

In the Linux kernel, the following vulnerability has been resolved: netfilter: ipset: fix performance regression in swap operation The patch "netfilter: ipset: fix race condition between swap/destroy and kernel side add/del/test", commit 28628fa9 fixes a race condition. But the synchronize_rcu() added to the swap function unnecessarily slows it down: it can safely be moved to destroy and use call_rcu() instead. Eric Dumazet pointed out that simply calling the destroy functions as rcu callback does not work: sets with timeout use garbage collectors which need cancelling at destroy which can wait. Therefore the destroy functions are split into two: cancelling garbage collectors safely at executing the command received by netlink and moving the remaining part only into the rcu callback.

The shm_get_stat function in ipc/shm.c in the shm subsystem in the Linux kernel before 2.6.28.5, when CONFIG_SHMEM is disabled, misinterprets the data type of an inode, which allows local users to cause a denial of service (system hang) via an SHM_INFO shmctl call, as demonstrated by running the ipcs program.

In the Linux kernel, the following vulnerability has been resolved: blk-mq: fix IO hang from sbitmap wakeup race In blk_mq_mark_tag_wait(), __add_wait_queue() may be re-ordered with the following blk_mq_get_driver_tag() in case of getting driver tag failure. Then in __sbitmap_queue_wake_up(), waitqueue_active() may not observe the added waiter in blk_mq_mark_tag_wait() and wake up nothing, meantime blk_mq_mark_tag_wait() can't get driver tag successfully. This issue can be reproduced by running the following test in loop, and fio hang can be observed in < 30min when running it on my test VM in laptop. modprobe -r scsi_debug modprobe scsi_debug delay=0 dev_size_mb=4096 max_queue=1 host_max_queue=1 submit_queues=4 dev=`ls -d /sys/bus/pseudo/drivers/scsi_debug/adapter*/host*/target*/*/block/* | head -1 | xargs basename` fio --filename=/dev/"$dev" --direct=1 --rw=randrw --bs=4k --iodepth=1 \ --runtime=100 --numjobs=40 --time_based --name=test \ --ioengine=libaio Fix the issue by adding one explicit barrier in blk_mq_mark_tag_wait(), which is just fine in case of running out of tag.

The (1) hugetlb_vmtruncate_list and (2) hugetlb_vmtruncate functions in fs/hugetlbfs/inode.c in the Linux kernel before 2.6.19-rc4 perform certain prio_tree calculations using HPAGE_SIZE instead of PAGE_SIZE units, which allows local users to cause a denial of service (panic) via unspecified vectors.

The inotify_read function in the Linux kernel 2.6.27 to 2.6.27.13, 2.6.28 to 2.6.28.2, and 2.6.29-rc3 allows local users to cause a denial of service (OOPS) via a read with an invalid address to an inotify instance, which causes the device's event list mutex to be unlocked twice and prevents proper synchronization of a data structure for the inotify instance.

v9fs_wstat in hw/9pfs/9p.c in QEMU allows guest OS users to cause a denial of service (crash) because of a race condition during file renaming.

An issue was discovered in the Linux kernel before 5.11.7. usbip_sockfd_store in drivers/usb/usbip/stub_dev.c allows attackers to cause a denial of service (GPF) because the stub-up sequence has race conditions during an update of the local and shared status, aka CID-9380afd6df70.

A race condition was discovered in get_old_root in fs/btrfs/ctree.c in the Linux kernel through 5.11.8. It allows attackers to cause a denial of service (BUG) because of a lack of locking on an extent buffer before a cloning operation, aka CID-dbcc7d57bffc.

An issue was discovered in the Linux kernel through 5.11.10. drivers/net/ethernet/freescale/gianfar.c in the Freescale Gianfar Ethernet driver allows attackers to cause a system crash because a negative fragment size is calculated in situations involving an rx queue overrun when jumbo packets are used and NAPI is enabled, aka CID-d8861bab48b6.

An issue was discovered in the Linux kernel before 6.2.9. A use-after-free was found in bq24190_remove in drivers/power/supply/bq24190_charger.c. It could allow a local attacker to crash the system due to a race condition.

In the Linux kernel, the following vulnerability has been resolved: USB: gadgetfs: Fix race between mounting and unmounting The syzbot fuzzer and Gerald Lee have identified a use-after-free bug in the gadgetfs driver, involving processes concurrently mounting and unmounting the gadgetfs filesystem. In particular, gadgetfs_fill_super() can race with gadgetfs_kill_sb(), causing the latter to deallocate the_device while the former is using it. The output from KASAN says, in part: BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:102 [inline] BUG: KASAN: use-after-free in atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:176 [inline] BUG: KASAN: use-after-free in __refcount_sub_and_test include/linux/refcount.h:272 [inline] BUG: KASAN: use-after-free in __refcount_dec_and_test include/linux/refcount.h:315 [inline] BUG: KASAN: use-after-free in refcount_dec_and_test include/linux/refcount.h:333 [inline] BUG: KASAN: use-after-free in put_dev drivers/usb/gadget/legacy/inode.c:159 [inline] BUG: KASAN: use-after-free in gadgetfs_kill_sb+0x33/0x100 drivers/usb/gadget/legacy/inode.c:2086 Write of size 4 at addr ffff8880276d7840 by task syz-executor126/18689 CPU: 0 PID: 18689 Comm: syz-executor126 Not tainted 6.1.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: <TASK> ... atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:176 [inline] __refcount_sub_and_test include/linux/refcount.h:272 [inline] __refcount_dec_and_test include/linux/refcount.h:315 [inline] refcount_dec_and_test include/linux/refcount.h:333 [inline] put_dev drivers/usb/gadget/legacy/inode.c:159 [inline] gadgetfs_kill_sb+0x33/0x100 drivers/usb/gadget/legacy/inode.c:2086 deactivate_locked_super+0xa7/0xf0 fs/super.c:332 vfs_get_super fs/super.c:1190 [inline] get_tree_single+0xd0/0x160 fs/super.c:1207 vfs_get_tree+0x88/0x270 fs/super.c:1531 vfs_fsconfig_locked fs/fsopen.c:232 [inline] The simplest solution is to ensure that gadgetfs_fill_super() and gadgetfs_kill_sb() are serialized by making them both acquire a new mutex.

A use-after-free flaw was found in the Linux kernel's Memory Management subsystem when a user wins two races at the same time with a fail in the mas_prev_slot function. This issue could allow a local user to crash the system.

An issue was discovered in Xen through 4.13.x, allowing x86 HVM guest OS users to cause a hypervisor crash. An inverted conditional in x86 HVM guests' dirty video RAM tracking code allows such guests to make Xen de-reference a pointer guaranteed to point at unmapped space. A malicious or buggy HVM guest may cause the hypervisor to crash, resulting in Denial of Service (DoS) affecting the entire host. Xen versions from 4.8 onwards are affected. Xen versions 4.7 and earlier are not affected. Only x86 systems are affected. Arm systems are not affected. Only x86 HVM guests using shadow paging can leverage the vulnerability. In addition, there needs to be an entity actively monitoring a guest's video frame buffer (typically for display purposes) in order for such a guest to be able to leverage the vulnerability. x86 PV guests, as well as x86 HVM guests using hardware assisted paging (HAP), cannot leverage the vulnerability.

A flaw was found in the Linux kernel before 5.9-rc4. A failure of the file system metadata validator in XFS can cause an inode with a valid, user-creatable extended attribute to be flagged as corrupt. This can lead to the filesystem being shutdown, or otherwise rendered inaccessible until it is remounted, leading to a denial of service. The highest threat from this vulnerability is to system availability.

In the Linux kernel before 5.4.16, a race condition in tty->disc_data handling in the slip and slcan line discipline could lead to a use-after-free, aka CID-0ace17d56824. This affects drivers/net/slip/slip.c and drivers/net/can/slcan.c.

The VFIO PCI driver in the Linux kernel through 5.6.13 mishandles attempts to access disabled memory space.

The __mptctl_ioctl function in drivers/message/fusion/mptctl.c in the Linux kernel before 5.4.14 allows local users to hold an incorrect lock during the ioctl operation and trigger a race condition, i.e., a "double fetch" vulnerability, aka CID-28d76df18f0a. NOTE: the vendor states "The security impact of this bug is not as bad as it could have been because these operations are all privileged and root already has enormous destructive power."

A pivot_root race condition in fs/namespace.c in the Linux kernel 4.4.x before 4.4.221, 4.9.x before 4.9.221, 4.14.x before 4.14.178, 4.19.x before 4.19.119, and 5.x before 5.3 allows local users to cause a denial of service (panic) by corrupting a mountpoint reference counter.

In the Linux kernel, the following vulnerability has been resolved: HID: logitech-hidpp: Fix kernel crash on receiver USB disconnect hidpp_connect_event() has *four* time-of-check vs time-of-use (TOCTOU) races when it races with itself. hidpp_connect_event() primarily runs from a workqueue but it also runs on probe() and if a "device-connected" packet is received by the hw when the thread running hidpp_connect_event() from probe() is waiting on the hw, then a second thread running hidpp_connect_event() will be started from the workqueue. This opens the following races (note the below code is simplified): 1. Retrieving + printing the protocol (harmless race): if (!hidpp->protocol_major) { hidpp_root_get_protocol_version() hidpp->protocol_major = response.rap.params[0]; } We can actually see this race hit in the dmesg in the abrt output attached to rhbz#2227968: [ 3064.624215] logitech-hidpp-device 0003:046D:4071.0049: HID++ 4.5 device connected. [ 3064.658184] logitech-hidpp-device 0003:046D:4071.0049: HID++ 4.5 device connected. Testing with extra logging added has shown that after this the 2 threads take turn grabbing the hw access mutex (send_mutex) so they ping-pong through all the other TOCTOU cases managing to hit all of them: 2. Updating the name to the HIDPP name (harmless race): if (hidpp->name == hdev->name) { ... hidpp->name = new_name; } 3. Initializing the power_supply class for the battery (problematic!): hidpp_initialize_battery() { if (hidpp->battery.ps) return 0; probe_battery(); /* Blocks, threads take turns executing this */ hidpp->battery.desc.properties = devm_kmemdup(dev, hidpp_battery_props, cnt, GFP_KERNEL); hidpp->battery.ps = devm_power_supply_register(&hidpp->hid_dev->dev, &hidpp->battery.desc, cfg); } 4. Creating delayed input_device (potentially problematic): if (hidpp->delayed_input) return; hidpp->delayed_input = hidpp_allocate_input(hdev); The really big problem here is 3. Hitting the race leads to the following sequence: hidpp->battery.desc.properties = devm_kmemdup(dev, hidpp_battery_props, cnt, GFP_KERNEL); hidpp->battery.ps = devm_power_supply_register(&hidpp->hid_dev->dev, &hidpp->battery.desc, cfg); ... hidpp->battery.desc.properties = devm_kmemdup(dev, hidpp_battery_props, cnt, GFP_KERNEL); hidpp->battery.ps = devm_power_supply_register(&hidpp->hid_dev->dev, &hidpp->battery.desc, cfg); So now we have registered 2 power supplies for the same battery, which looks a bit weird from userspace's pov but this is not even the really big problem. Notice how: 1. This is all devm-maganaged 2. The hidpp->battery.desc struct is shared between the 2 power supplies 3. hidpp->battery.desc.properties points to the result from the second devm_kmemdup() This causes a use after free scenario on USB disconnect of the receiver: 1. The last registered power supply class device gets unregistered 2. The memory from the last devm_kmemdup() call gets freed, hidpp->battery.desc.properties now points to freed memory 3. The first registered power supply class device gets unregistered, this involves sending a remove uevent to userspace which invokes power_supply_uevent() to fill the uevent data 4. power_supply_uevent() uses hidpp->battery.desc.properties which now points to freed memory leading to backtraces like this one: Sep 22 20:01:35 eric kernel: BUG: unable to handle page fault for address: ffffb2140e017f08 ... Sep 22 20:01:35 eric kernel: Workqueue: usb_hub_wq hub_event Sep 22 20:01:35 eric kernel: RIP: 0010:power_supply_uevent+0xee/0x1d0 ... Sep 22 20:01:35 eric kernel: ? asm_exc_page_fault+0x26/0x30 Sep 22 20:01:35 eric kernel: ? power_supply_uevent+0xee/0x1d0 Sep 22 20:01:35 eric kernel: ? power_supply_uevent+0x10d/0x1d0 Sep 22 20:01:35 eric kernel: dev_uevent+0x10f/0x2d0 Sep 22 20:01:35 eric kernel: kobject_uevent_env+0x291/0x680 Sep 22 20:01:35 eric kernel: ---truncated---

A flaw was found in the subsequent get_user_pages_fast in the Linux kernel’s interface for symmetric key cipher algorithms in the skcipher_recvmsg of crypto/algif_skcipher.c function. This flaw allows a local user to crash the system.