Race condition in the rds_sendmsg function in net/rds/sendmsg.c in the Linux kernel before 4.3.3 allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact by using a socket that was not properly bound. NOTE: this vulnerability exists because of an incomplete fix for CVE-2015-6937.

An issue was discovered in the Linux kernel before 6.3.2. A use-after-free was found in rkvdec_remove in drivers/staging/media/rkvdec/rkvdec.c.

An issue was discovered in the Linux kernel before 6.3.2. A use-after-free was found in saa7134_finidev in drivers/media/pci/saa7134/saa7134-core.c.

A race condition occurred between the functions lmLogClose and txEnd in JFS, in the Linux Kernel, executed in different threads. This flaw allows a local attacker with normal user privileges to crash the system or leak internal kernel information.

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix race in read_extent_buffer_pages() There are reports from tree-checker that detects corrupted nodes, without any obvious pattern so possibly an overwrite in memory. After some debugging it turns out there's a race when reading an extent buffer the uptodate status can be missed. To prevent concurrent reads for the same extent buffer, read_extent_buffer_pages() performs these checks: /* (1) */ if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags)) return 0; /* (2) */ if (test_and_set_bit(EXTENT_BUFFER_READING, &eb->bflags)) goto done; At this point, it seems safe to start the actual read operation. Once that completes, end_bbio_meta_read() does /* (3) */ set_extent_buffer_uptodate(eb); /* (4) */ clear_bit(EXTENT_BUFFER_READING, &eb->bflags); Normally, this is enough to ensure only one read happens, and all other callers wait for it to finish before returning. Unfortunately, there is a racey interleaving: Thread A | Thread B | Thread C ---------+----------+--------- (1) | | | (1) | (2) | | (3) | | (4) | | | (2) | | | (1) When this happens, thread B kicks of an unnecessary read. Worse, thread C will see UPTODATE set and return immediately, while the read from thread B is still in progress. This race could result in tree-checker errors like this as the extent buffer is concurrently modified: BTRFS critical (device dm-0): corrupted node, root=256 block=8550954455682405139 owner mismatch, have 11858205567642294356 expect [256, 18446744073709551360] Fix it by testing UPTODATE again after setting the READING bit, and if it's been set, skip the unnecessary read. [ minor update of changelog ]

sound/core/timer.c in the Linux kernel before 4.4.1 employs a locking approach that does not consider slave timer instances, which allows local users to cause a denial of service (race condition, use-after-free, and system crash) via a crafted ioctl call.

In the Linux kernel, the following vulnerability has been resolved: mm/mremap: fix move_normal_pmd/retract_page_tables race In mremap(), move_page_tables() looks at the type of the PMD entry and the specified address range to figure out by which method the next chunk of page table entries should be moved. At that point, the mmap_lock is held in write mode, but no rmap locks are held yet. For PMD entries that point to page tables and are fully covered by the source address range, move_pgt_entry(NORMAL_PMD, ...) is called, which first takes rmap locks, then does move_normal_pmd(). move_normal_pmd() takes the necessary page table locks at source and destination, then moves an entire page table from the source to the destination. The problem is: The rmap locks, which protect against concurrent page table removal by retract_page_tables() in the THP code, are only taken after the PMD entry has been read and it has been decided how to move it. So we can race as follows (with two processes that have mappings of the same tmpfs file that is stored on a tmpfs mount with huge=advise); note that process A accesses page tables through the MM while process B does it through the file rmap: process A process B ========= ========= mremap mremap_to move_vma move_page_tables get_old_pmd alloc_new_pmd *** PREEMPT *** madvise(MADV_COLLAPSE) do_madvise madvise_walk_vmas madvise_vma_behavior madvise_collapse hpage_collapse_scan_file collapse_file retract_page_tables i_mmap_lock_read(mapping) pmdp_collapse_flush i_mmap_unlock_read(mapping) move_pgt_entry(NORMAL_PMD, ...) take_rmap_locks move_normal_pmd drop_rmap_locks When this happens, move_normal_pmd() can end up creating bogus PMD entries in the line `pmd_populate(mm, new_pmd, pmd_pgtable(pmd))`. The effect depends on arch-specific and machine-specific details; on x86, you can end up with physical page 0 mapped as a page table, which is likely exploitable for user->kernel privilege escalation. Fix the race by letting process B recheck that the PMD still points to a page table after the rmap locks have been taken. Otherwise, we bail and let the caller fall back to the PTE-level copying path, which will then bail immediately at the pmd_none() check. Bug reachability: Reaching this bug requires that you can create shmem/file THP mappings - anonymous THP uses different code that doesn't zap stuff under rmap locks. File THP is gated on an experimental config flag (CONFIG_READ_ONLY_THP_FOR_FS), so on normal distro kernels you need shmem THP to hit this bug. As far as I know, getting shmem THP normally requires that you can mount your own tmpfs with the right mount flags, which would require creating your own user+mount namespace; though I don't know if some distros maybe enable shmem THP by default or something like that. Bug impact: This issue can likely be used for user->kernel privilege escalation when it is reachable.

The Linux kernel before 6.2.9 has a race condition and resultant use-after-free in drivers/net/ethernet/qualcomm/emac/emac.c if a physically proximate attacker unplugs an emac based device.

Multiple race conditions in the Advanced Union Filesystem (aufs) aufs3-mmap.patch and aufs4-mmap.patch patches for the Linux kernel 3.x and 4.x allow local users to cause a denial of service (use-after-free and BUG) or possibly gain privileges via a (1) madvise or (2) msync system call, related to mm/madvise.c and mm/msync.c.

In the Linux kernel, the following vulnerability has been resolved: net: phylink: add lock for serializing concurrent pl->phydev writes with resolver Currently phylink_resolve() protects itself against concurrent phylink_bringup_phy() or phylink_disconnect_phy() calls which modify pl->phydev by relying on pl->state_mutex. The problem is that in phylink_resolve(), pl->state_mutex is in a lock inversion state with pl->phydev->lock. So pl->phydev->lock needs to be acquired prior to pl->state_mutex. But that requires dereferencing pl->phydev in the first place, and without pl->state_mutex, that is racy. Hence the reason for the extra lock. Currently it is redundant, but it will serve a functional purpose once mutex_lock(&phy->lock) will be moved outside of the mutex_lock(&pl->state_mutex) section. Another alternative considered would have been to let phylink_resolve() acquire the rtnl_mutex, which is also held when phylink_bringup_phy() and phylink_disconnect_phy() are called. But since phylink_disconnect_phy() runs under rtnl_lock(), it would deadlock with phylink_resolve() when calling flush_work(&pl->resolve). Additionally, it would have been undesirable because it would have unnecessarily blocked many other call paths as well in the entire kernel, so the smaller-scoped lock was preferred.

In the Linux kernel, the following vulnerability has been resolved: iommu/amd/pgtbl: Fix possible race while increase page table level The AMD IOMMU host page table implementation supports dynamic page table levels (up to 6 levels), starting with a 3-level configuration that expands based on IOVA address. The kernel maintains a root pointer and current page table level to enable proper page table walks in alloc_pte()/fetch_pte() operations. The IOMMU IOVA allocator initially starts with 32-bit address and onces its exhuasted it switches to 64-bit address (max address is determined based on IOMMU and device DMA capability). To support larger IOVA, AMD IOMMU driver increases page table level. But in unmap path (iommu_v1_unmap_pages()), fetch_pte() reads pgtable->[root/mode] without lock. So its possible that in exteme corner case, when increase_address_space() is updating pgtable->[root/mode], fetch_pte() reads wrong page table level (pgtable->mode). It does compare the value with level encoded in page table and returns NULL. This will result is iommu_unmap ops to fail and upper layer may retry/log WARN_ON. CPU 0 CPU 1 ------ ------ map pages unmap pages alloc_pte() -> increase_address_space() iommu_v1_unmap_pages() -> fetch_pte() pgtable->root = pte (new root value) READ pgtable->[mode/root] Reads new root, old mode Updates mode (pgtable->mode += 1) Since Page table level updates are infrequent and already synchronized with a spinlock, implement seqcount to enable lock-free read operations on the read path.

In the Linux kernel, the following vulnerability has been resolved: ceph: fix race condition validating r_parent before applying state Add validation to ensure the cached parent directory inode matches the directory info in MDS replies. This prevents client-side race conditions where concurrent operations (e.g. rename) cause r_parent to become stale between request initiation and reply processing, which could lead to applying state changes to incorrect directory inodes. [ idryomov: folded a kerneldoc fixup and a follow-up fix from Alex to move CEPH_CAP_PIN reference when r_parent is updated: When the parent directory lock is not held, req->r_parent can become stale and is updated to point to the correct inode. However, the associated CEPH_CAP_PIN reference was not being adjusted. The CEPH_CAP_PIN is a reference on an inode that is tracked for accounting purposes. Moving this pin is important to keep the accounting balanced. When the pin was not moved from the old parent to the new one, it created two problems: The reference on the old, stale parent was never released, causing a reference leak. A reference for the new parent was never acquired, creating the risk of a reference underflow later in ceph_mdsc_release_request(). This patch corrects the logic by releasing the pin from the old parent and acquiring it for the new parent when r_parent is switched. This ensures reference accounting stays balanced. ]

In the Linux kernel, the following vulnerability has been resolved: NFS: Fix a race when updating an existing write After nfs_lock_and_join_requests() tests for whether the request is still attached to the mapping, nothing prevents a call to nfs_inode_remove_request() from succeeding until we actually lock the page group. The reason is that whoever called nfs_inode_remove_request() doesn't necessarily have a lock on the page group head. So in order to avoid races, let's take the page group lock earlier in nfs_lock_and_join_requests(), and hold it across the removal of the request in nfs_inode_remove_request().

In the Linux kernel, the following vulnerability has been resolved: mm/smaps: fix race between smaps_hugetlb_range and migration smaps_hugetlb_range() handles the pte without holdling ptl, and may be concurrenct with migration, leaing to BUG_ON in pfn_swap_entry_to_page(). The race is as follows. smaps_hugetlb_range migrate_pages huge_ptep_get remove_migration_ptes folio_unlock pfn_swap_entry_folio BUG_ON To fix it, hold ptl lock in smaps_hugetlb_range().

In the Linux kernel, the following vulnerability has been resolved: xfrm: state: initialize state_ptrs earlier in xfrm_state_find In case of preemption, xfrm_state_look_at will find a different pcpu_id and look up states for that other CPU. If we matched a state for CPU2 in the state_cache while the lookup started on CPU1, we will jump to "found", but the "best" state that we got will be ignored and we will enter the "acquire" block. This block uses state_ptrs, which isn't initialized at this point. Let's initialize state_ptrs just after taking rcu_read_lock. This will also prevent a possible misuse in the future, if someone adjusts this function.

In the Linux kernel, the following vulnerability has been resolved: net: kcm: Fix race condition in kcm_unattach() syzbot found a race condition when kcm_unattach(psock) and kcm_release(kcm) are executed at the same time. kcm_unattach() is missing a check of the flag kcm->tx_stopped before calling queue_work(). If the kcm has a reserved psock, kcm_unattach() might get executed between cancel_work_sync() and unreserve_psock() in kcm_release(), requeuing kcm->tx_work right before kcm gets freed in kcm_done(). Remove kcm->tx_stopped and replace it by the less error-prone disable_work_sync().

In the Linux kernel, the following vulnerability has been resolved: ppp: fix race conditions in ppp_fill_forward_path ppp_fill_forward_path() has two race conditions: 1. The ppp->channels list can change between list_empty() and list_first_entry(), as ppp_lock() is not held. If the only channel is deleted in ppp_disconnect_channel(), list_first_entry() may access an empty head or a freed entry, and trigger a panic. 2. pch->chan can be NULL. When ppp_unregister_channel() is called, pch->chan is set to NULL before pch is removed from ppp->channels. Fix these by using a lockless RCU approach: - Use list_first_or_null_rcu() to safely test and access the first list entry. - Convert list modifications on ppp->channels to their RCU variants and add synchronize_net() after removal. - Check for a NULL pch->chan before dereferencing it.

In the Linux kernel, the following vulnerability has been resolved: btrfs: qgroup: fix race between quota disable and quota rescan ioctl There's a race between a task disabling quotas and another running the rescan ioctl that can result in a use-after-free of qgroup records from the fs_info->qgroup_tree rbtree. This happens as follows: 1) Task A enters btrfs_ioctl_quota_rescan() -> btrfs_qgroup_rescan(); 2) Task B enters btrfs_quota_disable() and calls btrfs_qgroup_wait_for_completion(), which does nothing because at that point fs_info->qgroup_rescan_running is false (it wasn't set yet by task A); 3) Task B calls btrfs_free_qgroup_config() which starts freeing qgroups from fs_info->qgroup_tree without taking the lock fs_info->qgroup_lock; 4) Task A enters qgroup_rescan_zero_tracking() which starts iterating the fs_info->qgroup_tree tree while holding fs_info->qgroup_lock, but task B is freeing qgroup records from that tree without holding the lock, resulting in a use-after-free. Fix this by taking fs_info->qgroup_lock at btrfs_free_qgroup_config(). Also at btrfs_qgroup_rescan() don't start the rescan worker if quotas were already disabled.

In the Linux kernel, the following vulnerability has been resolved: pinmux: fix race causing mux_owner NULL with active mux_usecount commit 5a3e85c3c397 ("pinmux: Use sequential access to access desc->pinmux data") tried to address the issue when two client of the same gpio calls pinctrl_select_state() for the same functionality, was resulting in NULL pointer issue while accessing desc->mux_owner. However, issue was not completely fixed due to the way it was handled and it can still result in the same NULL pointer. The issue occurs due to the following interleaving: cpu0 (process A) cpu1 (process B) pin_request() { pin_free() { mutex_lock() desc->mux_usecount--; //becomes 0 .. mutex_unlock() mutex_lock(desc->mux) desc->mux_usecount++; // becomes 1 desc->mux_owner = owner; mutex_unlock(desc->mux) mutex_lock(desc->mux) desc->mux_owner = NULL; mutex_unlock(desc->mux) This sequence leads to a state where the pin appears to be in use (`mux_usecount == 1`) but has no owner (`mux_owner == NULL`), which can cause NULL pointer on next pin_request on the same pin. Ensure that updates to mux_usecount and mux_owner are performed atomically under the same lock. Only clear mux_owner when mux_usecount reaches zero and no new owner has been assigned.

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix a race between renames and directory logging We have a race between a rename and directory inode logging that if it happens and we crash/power fail before the rename completes, the next time the filesystem is mounted, the log replay code will end up deleting the file that was being renamed. This is best explained following a step by step analysis of an interleaving of steps that lead into this situation. Consider the initial conditions: 1) We are at transaction N; 2) We have directories A and B created in a past transaction (< N); 3) We have inode X corresponding to a file that has 2 hardlinks, one in directory A and the other in directory B, so we'll name them as "A/foo_link1" and "B/foo_link2". Both hard links were persisted in a past transaction (< N); 4) We have inode Y corresponding to a file that as a single hard link and is located in directory A, we'll name it as "A/bar". This file was also persisted in a past transaction (< N). The steps leading to a file loss are the following and for all of them we are under transaction N: 1) Link "A/foo_link1" is removed, so inode's X last_unlink_trans field is updated to N, through btrfs_unlink() -> btrfs_record_unlink_dir(); 2) Task A starts a rename for inode Y, with the goal of renaming from "A/bar" to "A/baz", so we enter btrfs_rename(); 3) Task A inserts the new BTRFS_INODE_REF_KEY for inode Y by calling btrfs_insert_inode_ref(); 4) Because the rename happens in the same directory, we don't set the last_unlink_trans field of directoty A's inode to the current transaction id, that is, we don't cal btrfs_record_unlink_dir(); 5) Task A then removes the entries from directory A (BTRFS_DIR_ITEM_KEY and BTRFS_DIR_INDEX_KEY items) when calling __btrfs_unlink_inode() (actually the dir index item is added as a delayed item, but the effect is the same); 6) Now before task A adds the new entry "A/baz" to directory A by calling btrfs_add_link(), another task, task B is logging inode X; 7) Task B starts a fsync of inode X and after logging inode X, at btrfs_log_inode_parent() it calls btrfs_log_all_parents(), since inode X has a last_unlink_trans value of N, set at in step 1; 8) At btrfs_log_all_parents() we search for all parent directories of inode X using the commit root, so we find directories A and B and log them. Bu when logging direct A, we don't have a dir index item for inode Y anymore, neither the old name "A/bar" nor for the new name "A/baz" since the rename has deleted the old name but has not yet inserted the new name - task A hasn't called yet btrfs_add_link() to do that. Note that logging directory A doesn't fallback to a transaction commit because its last_unlink_trans has a lower value than the current transaction's id (see step 4); 9) Task B finishes logging directories A and B and gets back to btrfs_sync_file() where it calls btrfs_sync_log() to persist the log tree; 10) Task B successfully persisted the log tree, btrfs_sync_log() completed with success, and a power failure happened. We have a log tree without any directory entry for inode Y, so the log replay code deletes the entry for inode Y, name "A/bar", from the subvolume tree since it doesn't exist in the log tree and the log tree is authorative for its index (we logged a BTRFS_DIR_LOG_INDEX_KEY item that covers the index range for the dentry that corresponds to "A/bar"). Since there's no other hard link for inode Y and the log replay code deletes the name "A/bar", the file is lost. The issue wouldn't happen if task B synced the log only after task A called btrfs_log_new_name(), which would update the log with the new name for inode Y ("A/bar"). Fix this by pinning the log root during renames before removing the old directory entry, and unpinning af ---truncated---

In the Linux kernel, the following vulnerability has been resolved: mm/hugetlb: fix huge_pmd_unshare() vs GUP-fast race huge_pmd_unshare() drops a reference on a page table that may have previously been shared across processes, potentially turning it into a normal page table used in another process in which unrelated VMAs can afterwards be installed. If this happens in the middle of a concurrent gup_fast(), gup_fast() could end up walking the page tables of another process. While I don't see any way in which that immediately leads to kernel memory corruption, it is really weird and unexpected. Fix it with an explicit broadcast IPI through tlb_remove_table_sync_one(), just like we do in khugepaged when removing page tables for a THP collapse.

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix Preauh_HashValue race condition If client send multiple session setup requests to ksmbd, Preauh_HashValue race condition could happen. There is no need to free sess->Preauh_HashValue at session setup phase. It can be freed together with session at connection termination phase.

In the Linux kernel, the following vulnerability has been resolved: net_sched: prio: fix a race in prio_tune() Gerrard Tai reported a race condition in PRIO, whenever SFQ perturb timer fires at the wrong time. The race is as follows: CPU 0 CPU 1 [1]: lock root [2]: qdisc_tree_flush_backlog() [3]: unlock root | | [5]: lock root | [6]: rehash | [7]: qdisc_tree_reduce_backlog() | [4]: qdisc_put() This can be abused to underflow a parent's qlen. Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog() should fix the race, because all packets will be purged from the qdisc before releasing the lock.

In the Linux kernel, the following vulnerability has been resolved: sched/rt: Fix race in push_rt_task Overview ======== When a CPU chooses to call push_rt_task and picks a task to push to another CPU's runqueue then it will call find_lock_lowest_rq method which would take a double lock on both CPUs' runqueues. If one of the locks aren't readily available, it may lead to dropping the current runqueue lock and reacquiring both the locks at once. During this window it is possible that the task is already migrated and is running on some other CPU. These cases are already handled. However, if the task is migrated and has already been executed and another CPU is now trying to wake it up (ttwu) such that it is queued again on the runqeue (on_rq is 1) and also if the task was run by the same CPU, then the current checks will pass even though the task was migrated out and is no longer in the pushable tasks list. Crashes ======= This bug resulted in quite a few flavors of crashes triggering kernel panics with various crash signatures such as assert failures, page faults, null pointer dereferences, and queue corruption errors all coming from scheduler itself. Some of the crashes: -> kernel BUG at kernel/sched/rt.c:1616! BUG_ON(idx >= MAX_RT_PRIO) Call Trace: ? __die_body+0x1a/0x60 ? die+0x2a/0x50 ? do_trap+0x85/0x100 ? pick_next_task_rt+0x6e/0x1d0 ? do_error_trap+0x64/0xa0 ? pick_next_task_rt+0x6e/0x1d0 ? exc_invalid_op+0x4c/0x60 ? pick_next_task_rt+0x6e/0x1d0 ? asm_exc_invalid_op+0x12/0x20 ? pick_next_task_rt+0x6e/0x1d0 __schedule+0x5cb/0x790 ? update_ts_time_stats+0x55/0x70 schedule_idle+0x1e/0x40 do_idle+0x15e/0x200 cpu_startup_entry+0x19/0x20 start_secondary+0x117/0x160 secondary_startup_64_no_verify+0xb0/0xbb -> BUG: kernel NULL pointer dereference, address: 00000000000000c0 Call Trace: ? __die_body+0x1a/0x60 ? no_context+0x183/0x350 ? __warn+0x8a/0xe0 ? exc_page_fault+0x3d6/0x520 ? asm_exc_page_fault+0x1e/0x30 ? pick_next_task_rt+0xb5/0x1d0 ? pick_next_task_rt+0x8c/0x1d0 __schedule+0x583/0x7e0 ? update_ts_time_stats+0x55/0x70 schedule_idle+0x1e/0x40 do_idle+0x15e/0x200 cpu_startup_entry+0x19/0x20 start_secondary+0x117/0x160 secondary_startup_64_no_verify+0xb0/0xbb -> BUG: unable to handle page fault for address: ffff9464daea5900 kernel BUG at kernel/sched/rt.c:1861! BUG_ON(rq->cpu != task_cpu(p)) -> kernel BUG at kernel/sched/rt.c:1055! BUG_ON(!rq->nr_running) Call Trace: ? __die_body+0x1a/0x60 ? die+0x2a/0x50 ? do_trap+0x85/0x100 ? dequeue_top_rt_rq+0xa2/0xb0 ? do_error_trap+0x64/0xa0 ? dequeue_top_rt_rq+0xa2/0xb0 ? exc_invalid_op+0x4c/0x60 ? dequeue_top_rt_rq+0xa2/0xb0 ? asm_exc_invalid_op+0x12/0x20 ? dequeue_top_rt_rq+0xa2/0xb0 dequeue_rt_entity+0x1f/0x70 dequeue_task_rt+0x2d/0x70 __schedule+0x1a8/0x7e0 ? blk_finish_plug+0x25/0x40 schedule+0x3c/0xb0 futex_wait_queue_me+0xb6/0x120 futex_wait+0xd9/0x240 do_futex+0x344/0xa90 ? get_mm_exe_file+0x30/0x60 ? audit_exe_compare+0x58/0x70 ? audit_filter_rules.constprop.26+0x65e/0x1220 __x64_sys_futex+0x148/0x1f0 do_syscall_64+0x30/0x80 entry_SYSCALL_64_after_hwframe+0x62/0xc7 -> BUG: unable to handle page fault for address: ffff8cf3608bc2c0 Call Trace: ? __die_body+0x1a/0x60 ? no_context+0x183/0x350 ? spurious_kernel_fault+0x171/0x1c0 ? exc_page_fault+0x3b6/0x520 ? plist_check_list+0x15/0x40 ? plist_check_list+0x2e/0x40 ? asm_exc_page_fault+0x1e/0x30 ? _cond_resched+0x15/0x30 ? futex_wait_queue_me+0xc8/0x120 ? futex_wait+0xd9/0x240 ? try_to_wake_up+0x1b8/0x490 ? futex_wake+0x78/0x160 ? do_futex+0xcd/0xa90 ? plist_check_list+0x15/0x40 ? plist_check_list+0x2e/0x40 ? plist_del+0x6a/0xd0 ? plist_check_list+0x15/0x40 ? plist_check_list+0x2e/0x40 ? dequeue_pushable_task+0x20/0x70 ? __schedule+0x382/0x7e0 ? asm_sysvec_reschedule_i ---truncated---

In the Linux kernel, the following vulnerability has been resolved: NFS/localio: Fix a race in nfs_local_open_fh() Once the clp->cl_uuid.lock has been dropped, another CPU could come in and free the struct nfsd_file that was just added. To prevent that from happening, take the RCU read lock before dropping the spin lock.

In the Linux kernel, the following vulnerability has been resolved: mm/vmalloc: fix data race in show_numa_info() The following data-race was found in show_numa_info(): ================================================================== BUG: KCSAN: data-race in vmalloc_info_show / vmalloc_info_show read to 0xffff88800971fe30 of 4 bytes by task 8289 on cpu 0: show_numa_info mm/vmalloc.c:4936 [inline] vmalloc_info_show+0x5a8/0x7e0 mm/vmalloc.c:5016 seq_read_iter+0x373/0xb40 fs/seq_file.c:230 proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 .... write to 0xffff88800971fe30 of 4 bytes by task 8287 on cpu 1: show_numa_info mm/vmalloc.c:4934 [inline] vmalloc_info_show+0x38f/0x7e0 mm/vmalloc.c:5016 seq_read_iter+0x373/0xb40 fs/seq_file.c:230 proc_reg_read_iter+0x11e/0x170 fs/proc/inode.c:299 .... value changed: 0x0000008f -> 0x00000000 ================================================================== According to this report,there is a read/write data-race because m->private is accessible to multiple CPUs. To fix this, instead of allocating the heap in proc_vmalloc_init() and passing the heap address to m->private, vmalloc_info_show() should allocate the heap.

In the Linux kernel, the following vulnerability has been resolved: VMCI: fix race between vmci_host_setup_notify and vmci_ctx_unset_notify During our test, it is found that a warning can be trigger in try_grab_folio as follow: ------------[ cut here ]------------ WARNING: CPU: 0 PID: 1678 at mm/gup.c:147 try_grab_folio+0x106/0x130 Modules linked in: CPU: 0 UID: 0 PID: 1678 Comm: syz.3.31 Not tainted 6.15.0-rc5 #163 PREEMPT(undef) RIP: 0010:try_grab_folio+0x106/0x130 Call Trace: <TASK> follow_huge_pmd+0x240/0x8e0 follow_pmd_mask.constprop.0.isra.0+0x40b/0x5c0 follow_pud_mask.constprop.0.isra.0+0x14a/0x170 follow_page_mask+0x1c2/0x1f0 __get_user_pages+0x176/0x950 __gup_longterm_locked+0x15b/0x1060 ? gup_fast+0x120/0x1f0 gup_fast_fallback+0x17e/0x230 get_user_pages_fast+0x5f/0x80 vmci_host_unlocked_ioctl+0x21c/0xf80 RIP: 0033:0x54d2cd ---[ end trace 0000000000000000 ]--- Digging into the source, context->notify_page may init by get_user_pages_fast and can be seen in vmci_ctx_unset_notify which will try to put_page. However get_user_pages_fast is not finished here and lead to following try_grab_folio warning. The race condition is shown as follow: cpu0 cpu1 vmci_host_do_set_notify vmci_host_setup_notify get_user_pages_fast(uva, 1, FOLL_WRITE, &context->notify_page); lockless_pages_from_mm gup_pgd_range gup_huge_pmd // update &context->notify_page vmci_host_do_set_notify vmci_ctx_unset_notify notify_page = context->notify_page; if (notify_page) put_page(notify_page); // page is freed __gup_longterm_locked __get_user_pages follow_trans_huge_pmd try_grab_folio // warn here To slove this, use local variable page to make notify_page can be seen after finish get_user_pages_fast.

In the Linux kernel, the following vulnerability has been resolved: mm/page_alloc: fix race condition in unaccepted memory handling The page allocator tracks the number of zones that have unaccepted memory using static_branch_enc/dec() and uses that static branch in hot paths to determine if it needs to deal with unaccepted memory. Borislav and Thomas pointed out that the tracking is racy: operations on static_branch are not serialized against adding/removing unaccepted pages to/from the zone. Sanity checks inside static_branch machinery detects it: WARNING: CPU: 0 PID: 10 at kernel/jump_label.c:276 __static_key_slow_dec_cpuslocked+0x8e/0xa0 The comment around the WARN() explains the problem: /* * Warn about the '-1' case though; since that means a * decrement is concurrent with a first (0->1) increment. IOW * people are trying to disable something that wasn't yet fully * enabled. This suggests an ordering problem on the user side. */ The effect of this static_branch optimization is only visible on microbenchmark. Instead of adding more complexity around it, remove it altogether.

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: u_serial: Fix race condition in TTY wakeup A race condition occurs when gs_start_io() calls either gs_start_rx() or gs_start_tx(), as those functions briefly drop the port_lock for usb_ep_queue(). This allows gs_close() and gserial_disconnect() to clear port.tty and port_usb, respectively. Use the null-safe TTY Port helper function to wake up TTY. Example CPU1: CPU2: gserial_connect() // lock gs_close() // await lock gs_start_rx() // unlock usb_ep_queue() gs_close() // lock, reset port.tty and unlock gs_start_rx() // lock tty_wakeup() // NPE

In the Linux kernel, the following vulnerability has been resolved: net_sched: red: fix a race in __red_change() Gerrard Tai reported a race condition in RED, whenever SFQ perturb timer fires at the wrong time. The race is as follows: CPU 0 CPU 1 [1]: lock root [2]: qdisc_tree_flush_backlog() [3]: unlock root | | [5]: lock root | [6]: rehash | [7]: qdisc_tree_reduce_backlog() | [4]: qdisc_put() This can be abused to underflow a parent's qlen. Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog() should fix the race, because all packets will be purged from the qdisc before releasing the lock.

In the Linux kernel, the following vulnerability has been resolved: ublk: fix race between io_uring_cmd_complete_in_task and ublk_cancel_cmd ublk_cancel_cmd() calls io_uring_cmd_done() to complete uring_cmd, but we may have scheduled task work via io_uring_cmd_complete_in_task() for dispatching request, then kernel crash can be triggered. Fix it by not trying to canceling the command if ublk block request is started.

A flaw was found in the Linux kernel's ksmbd, a high-performance in-kernel SMB server. The specific flaw exists within the processing of SMB2_TREE_DISCONNECT commands. The issue results from the lack of proper locking when performing operations on an object. An attacker can leverage this vulnerability to execute code in the context of the kernel.

In the Linux kernel, the following vulnerability has been resolved: USB: wdm: close race between wdm_open and wdm_wwan_port_stop Clearing WDM_WWAN_IN_USE must be the last action or we can open a chardev whose URBs are still poisoned

A flaw was found in the Linux kernel's ksmbd, a high-performance in-kernel SMB server. The specific flaw exists within the processing of SMB2_SESSION_SETUP and SMB2_LOGOFF commands. The issue results from the lack of proper locking when performing operations on an object. An attacker can leverage this vulnerability to execute code in the context of the kernel.

In the Linux kernel, the following vulnerability has been resolved: nfsd: avoid ref leak in nfsd_open_local_fh() If two calls to nfsd_open_local_fh() race and both successfully call nfsd_file_acquire_local(), they will both get an extra reference to the net to accompany the file reference stored in *pnf. One of them will fail to store (using xchg()) the file reference in *pnf and will drop that reference but WON'T drop the accompanying reference to the net. This leak means that when the nfs server is shut down it will hang in nfsd_shutdown_net() waiting for &nn->nfsd_net_free_done. This patch adds the missing nfsd_net_put().

A flaw was found in the Linux kernel's ksmbd, a high-performance in-kernel SMB server. The specific flaw exists within the processing of SMB2_LOGOFF and SMB2_CLOSE commands. The issue results from the lack of proper locking when performing operations on an object. An attacker can leverage this vulnerability to execute code in the context of the kernel.

In the Linux kernel, the following vulnerability has been resolved: wifi: ath12k: fix node corruption in ar->arvifs list In current WLAN recovery code flow, ath12k_core_halt() only reinitializes the "arvifs" list head. This will cause the list node immediately following the list head to become an invalid list node. Because the prev of that node still points to the list head "arvifs", but the next of the list head "arvifs" no longer points to that list node. When a WLAN recovery occurs during the execution of a vif removal, and it happens before the spin_lock_bh(&ar->data_lock) in ath12k_mac_vdev_delete(), list_del() will detect the previously mentioned situation, thereby triggering a kernel panic. The fix is to remove and reinitialize all vif list nodes from the list head "arvifs" during WLAN halt. The reinitialization is to make the list nodes valid, ensuring that the list_del() in ath12k_mac_vdev_delete() can execute normally. Call trace: __list_del_entry_valid_or_report+0xd4/0x100 (P) ath12k_mac_remove_link_interface.isra.0+0xf8/0x2e4 [ath12k] ath12k_scan_vdev_clean_work+0x40/0x164 [ath12k] cfg80211_wiphy_work+0xfc/0x100 process_one_work+0x164/0x2d0 worker_thread+0x254/0x380 kthread+0xfc/0x100 ret_from_fork+0x10/0x20 The change is mostly copied from the ath11k patch: https://lore.kernel.org/all/20250320053145.3445187-1-quic_stonez@quicinc.com/ Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.4.1-00199-QCAHKSWPL_SILICONZ-1

In the Linux kernel, the following vulnerability has been resolved: mm: userfaultfd: fix race of userfaultfd_move and swap cache This commit fixes two kinds of races, they may have different results: Barry reported a BUG_ON in commit c50f8e6053b0, we may see the same BUG_ON if the filemap lookup returned NULL and folio is added to swap cache after that. If another kind of race is triggered (folio changed after lookup) we may see RSS counter is corrupted: [ 406.893936] BUG: Bad rss-counter state mm:ffff0000c5a9ddc0 type:MM_ANONPAGES val:-1 [ 406.894071] BUG: Bad rss-counter state mm:ffff0000c5a9ddc0 type:MM_SHMEMPAGES val:1 Because the folio is being accounted to the wrong VMA. I'm not sure if there will be any data corruption though, seems no. The issues above are critical already. On seeing a swap entry PTE, userfaultfd_move does a lockless swap cache lookup, and tries to move the found folio to the faulting vma. Currently, it relies on checking the PTE value to ensure that the moved folio still belongs to the src swap entry and that no new folio has been added to the swap cache, which turns out to be unreliable. While working and reviewing the swap table series with Barry, following existing races are observed and reproduced [1]: In the example below, move_pages_pte is moving src_pte to dst_pte, where src_pte is a swap entry PTE holding swap entry S1, and S1 is not in the swap cache: CPU1 CPU2 userfaultfd_move move_pages_pte() entry = pte_to_swp_entry(orig_src_pte); // Here it got entry = S1 ... < interrupted> ... <swapin src_pte, alloc and use folio A> // folio A is a new allocated folio // and get installed into src_pte <frees swap entry S1> // src_pte now points to folio A, S1 // has swap count == 0, it can be freed // by folio_swap_swap or swap // allocator's reclaim. <try to swap out another folio B> // folio B is a folio in another VMA. <put folio B to swap cache using S1 > // S1 is freed, folio B can use it // for swap out with no problem. ... folio = filemap_get_folio(S1) // Got folio B here !!! ... < interrupted again> ... <swapin folio B and free S1> // Now S1 is free to be used again. <swapout src_pte & folio A using S1> // Now src_pte is a swap entry PTE // holding S1 again. folio_trylock(folio) move_swap_pte double_pt_lock is_pte_pages_stable // Check passed because src_pte == S1 folio_move_anon_rmap(...) // Moved invalid folio B here !!! The race window is very short and requires multiple collisions of multiple rare events, so it's very unlikely to happen, but with a deliberately constructed reproducer and increased time window, it can be reproduced easily. This can be fixed by checking if the folio returned by filemap is the valid swap cache folio after acquiring the folio lock. Another similar race is possible: filemap_get_folio may return NULL, but folio (A) could be swapped in and then swapped out again using the same swap entry after the lookup. In such a case, folio (A) may remain in the swap cache, so it must be moved too: CPU1 CPU2 userfaultfd_move move_pages_pte() entry = pte_to_swp_entry(orig_src_pte); // Here it got entry = S1, and S1 is not in swap cache folio = filemap_get ---truncated---

In the Linux kernel, the following vulnerability has been resolved: fs/fhandle.c: fix a race in call of has_locked_children() may_decode_fh() is calling has_locked_children() while holding no locks. That's an oopsable race... The rest of the callers are safe since they are holding namespace_sem and are guaranteed a positive refcount on the mount in question. Rename the current has_locked_children() to __has_locked_children(), make it static and switch the fs/namespace.c users to it. Make has_locked_children() a wrapper for __has_locked_children(), calling the latter under read_seqlock_excl(&mount_lock).

In the Linux kernel, the following vulnerability has been resolved: net_sched: ets: fix a race in ets_qdisc_change() Gerrard Tai reported a race condition in ETS, whenever SFQ perturb timer fires at the wrong time. The race is as follows: CPU 0 CPU 1 [1]: lock root [2]: qdisc_tree_flush_backlog() [3]: unlock root | | [5]: lock root | [6]: rehash | [7]: qdisc_tree_reduce_backlog() | [4]: qdisc_put() This can be abused to underflow a parent's qlen. Calling qdisc_purge_queue() instead of qdisc_tree_flush_backlog() should fix the race, because all packets will be purged from the qdisc before releasing the lock.

In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: Fix race of buffer access at PCM OSS layer The PCM OSS layer tries to clear the buffer with the silence data at initialization (or reconfiguration) of a stream with the explicit call of snd_pcm_format_set_silence() with runtime->dma_area. But this may lead to a UAF because the accessed runtime->dma_area might be freed concurrently, as it's performed outside the PCM ops. For avoiding it, move the code into the PCM core and perform it inside the buffer access lock, so that it won't be changed during the operation.

In the Linux kernel, the following vulnerability has been resolved: virtio_ring: Fix data race by tagging event_triggered as racy for KCSAN syzbot reports a data-race when accessing the event_triggered, here is the simplified stack when the issue occurred: ================================================================== BUG: KCSAN: data-race in virtqueue_disable_cb / virtqueue_enable_cb_delayed write to 0xffff8881025bc452 of 1 bytes by task 3288 on cpu 0: virtqueue_enable_cb_delayed+0x42/0x3c0 drivers/virtio/virtio_ring.c:2653 start_xmit+0x230/0x1310 drivers/net/virtio_net.c:3264 __netdev_start_xmit include/linux/netdevice.h:5151 [inline] netdev_start_xmit include/linux/netdevice.h:5160 [inline] xmit_one net/core/dev.c:3800 [inline] read to 0xffff8881025bc452 of 1 bytes by interrupt on cpu 1: virtqueue_disable_cb_split drivers/virtio/virtio_ring.c:880 [inline] virtqueue_disable_cb+0x92/0x180 drivers/virtio/virtio_ring.c:2566 skb_xmit_done+0x5f/0x140 drivers/net/virtio_net.c:777 vring_interrupt+0x161/0x190 drivers/virtio/virtio_ring.c:2715 __handle_irq_event_percpu+0x95/0x490 kernel/irq/handle.c:158 handle_irq_event_percpu kernel/irq/handle.c:193 [inline] value changed: 0x01 -> 0x00 ================================================================== When the data race occurs, the function virtqueue_enable_cb_delayed() sets event_triggered to false, and virtqueue_disable_cb_split/packed() reads it as false due to the race condition. Since event_triggered is an unreliable hint used for optimization, this should only cause the driver temporarily suggest that the device not send an interrupt notification when the event index is used. Fix this KCSAN reported data-race issue by explicitly tagging the access as data_racy.

An issue was discovered in drivers/bluetooth/hci_ldisc.c in the Linux kernel 6.2. In hci_uart_tty_ioctl, there is a race condition between HCIUARTSETPROTO and HCIUARTGETPROTO. HCI_UART_PROTO_SET is set before hu->proto is set. A NULL pointer dereference may occur.

In the Linux kernel, the following vulnerability has been resolved: NFSD: fix race between nfsd registration and exports_proc As of now nfsd calls create_proc_exports_entry() at start of init_nfsd and cleanup by remove_proc_entry() at last of exit_nfsd. Which causes kernel OOPs if there is race between below 2 operations: (i) exportfs -r (ii) mount -t nfsd none /proc/fs/nfsd for 5.4 kernel ARM64: CPU 1: el1_irq+0xbc/0x180 arch_counter_get_cntvct+0x14/0x18 running_clock+0xc/0x18 preempt_count_add+0x88/0x110 prep_new_page+0xb0/0x220 get_page_from_freelist+0x2d8/0x1778 __alloc_pages_nodemask+0x15c/0xef0 __vmalloc_node_range+0x28c/0x478 __vmalloc_node_flags_caller+0x8c/0xb0 kvmalloc_node+0x88/0xe0 nfsd_init_net+0x6c/0x108 [nfsd] ops_init+0x44/0x170 register_pernet_operations+0x114/0x270 register_pernet_subsys+0x34/0x50 init_nfsd+0xa8/0x718 [nfsd] do_one_initcall+0x54/0x2e0 CPU 2 : Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 PC is at : exports_net_open+0x50/0x68 [nfsd] Call trace: exports_net_open+0x50/0x68 [nfsd] exports_proc_open+0x2c/0x38 [nfsd] proc_reg_open+0xb8/0x198 do_dentry_open+0x1c4/0x418 vfs_open+0x38/0x48 path_openat+0x28c/0xf18 do_filp_open+0x70/0xe8 do_sys_open+0x154/0x248 Sometimes it crashes at exports_net_open() and sometimes cache_seq_next_rcu(). and same is happening on latest 6.14 kernel as well: [ 0.000000] Linux version 6.14.0-rc5-next-20250304-dirty ... [ 285.455918] Unable to handle kernel paging request at virtual address 00001f4800001f48 ... [ 285.464902] pc : cache_seq_next_rcu+0x78/0xa4 ... [ 285.469695] Call trace: [ 285.470083] cache_seq_next_rcu+0x78/0xa4 (P) [ 285.470488] seq_read+0xe0/0x11c [ 285.470675] proc_reg_read+0x9c/0xf0 [ 285.470874] vfs_read+0xc4/0x2fc [ 285.471057] ksys_read+0x6c/0xf4 [ 285.471231] __arm64_sys_read+0x1c/0x28 [ 285.471428] invoke_syscall+0x44/0x100 [ 285.471633] el0_svc_common.constprop.0+0x40/0xe0 [ 285.471870] do_el0_svc_compat+0x1c/0x34 [ 285.472073] el0_svc_compat+0x2c/0x80 [ 285.472265] el0t_32_sync_handler+0x90/0x140 [ 285.472473] el0t_32_sync+0x19c/0x1a0 [ 285.472887] Code: f9400885 93407c23 937d7c27 11000421 (f86378a3) [ 285.473422] ---[ end trace 0000000000000000 ]--- It reproduced simply with below script: while [ 1 ] do /exportfs -r done & while [ 1 ] do insmod /nfsd.ko mount -t nfsd none /proc/fs/nfsd umount /proc/fs/nfsd rmmod nfsd done & So exporting interfaces to user space shall be done at last and cleanup at first place. With change there is no Kernel OOPs.

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.

In the Linux kernel, the following vulnerability has been resolved: fix a couple of races in MNT_TREE_BENEATH handling by do_move_mount() Normally do_lock_mount(path, _) is locking a mountpoint pinned by *path and at the time when matching unlock_mount() unlocks that location it is still pinned by the same thing. Unfortunately, for 'beneath' case it's no longer that simple - the object being locked is not the one *path points to. It's the mountpoint of path->mnt. The thing is, without sufficient locking ->mnt_parent may change under us and none of the locks are held at that point. The rules are * mount_lock stabilizes m->mnt_parent for any mount m. * namespace_sem stabilizes m->mnt_parent, provided that m is mounted. * if either of the above holds and refcount of m is positive, we are guaranteed the same for refcount of m->mnt_parent. namespace_sem nests inside inode_lock(), so do_lock_mount() has to take inode_lock() before grabbing namespace_sem. It does recheck that path->mnt is still mounted in the same place after getting namespace_sem, and it does take care to pin the dentry. It is needed, since otherwise we might end up with racing mount --move (or umount) happening while we were getting locks; in that case dentry would no longer be a mountpoint and could've been evicted on memory pressure along with its inode - not something you want when grabbing lock on that inode. However, pinning a dentry is not enough - the matching mount is also pinned only by the fact that path->mnt is mounted on top it and at that point we are not holding any locks whatsoever, so the same kind of races could end up with all references to that mount gone just as we are about to enter inode_lock(). If that happens, we are left with filesystem being shut down while we are holding a dentry reference on it; results are not pretty. What we need to do is grab both dentry and mount at the same time; that makes inode_lock() safe *and* avoids the problem with fs getting shut down under us. After taking namespace_sem we verify that path->mnt is still mounted (which stabilizes its ->mnt_parent) and check that it's still mounted at the same place. From that point on to the matching namespace_unlock() we are guaranteed that mount/dentry pair we'd grabbed are also pinned by being the mountpoint of path->mnt, so we can quietly drop both the dentry reference (as the current code does) and mnt one - it's OK to do under namespace_sem, since we are not dropping the final refs. That solves the problem on do_lock_mount() side; unlock_mount() also has one, since dentry is guaranteed to stay pinned only until the namespace_unlock(). That's easy to fix - just have inode_unlock() done earlier, while it's still pinned by mp->m_dentry.

NVIDIA Resiliency Extension for Linux contains a vulnerability in the checkpointing core, where an attacker may cause a race condition. A successful exploit of this vulnerability might lead to information disclosure, data tampering, denial of service, or escalation of privileges.

There is a null-pointer-dereference flaw found in f2fs_write_end_io in fs/f2fs/data.c in the Linux kernel. This flaw allows a local privileged user to cause a denial of service problem.

VMware Tools prior to 10.0.9 contains multiple file system races in libDeployPkg, related to the use of hard-coded paths under /tmp. Successful exploitation of this issue may result in a local privilege escalation. CVSS:3.0/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H

The Linux kernel before 2.4.36-rc1 has a race condition. It was possible to bypass systrace policies by flooding the ptraced process with SIGCONT signals, which can can wake up a PTRACED process.