Search Results (5389 CVEs found)

CVE Vendors Products Updated CVSS v3.1
CVE-2026-80847 1 Linux 1 Linux Kernel 2026-10-21 N/A
In the Linux kernel, the following vulnerability has been resolved: tcp: clamp route advmss to TCP_MIN_MSS tcp_select_initial_window() assumes that callers never pass an MSS smaller than 1, but route-derived advmss values can violate that assumption. A too-small explicit RTAX_ADVMSS is one way to get there, but it is not the only one. The same divide-by-zero can also be reached through the "default advmss" path when RTAX_ADVMSS is left at 0 and the effective advmss is later driven down by route MTU and min_adv_mss. Introduce a tcp_dst_advmss() helper that clamps route advmss to TCP_MIN_MSS before TCP consumes it, and use it in the TCP paths that derive advmss from dst metrics. This keeps the effective MSS from dropping to zero before tcp_select_initial_window() rounds the receive window.
CVE-2026-80653 1 Linux 1 Linux Kernel 2026-10-21 8.4 High
In the Linux kernel, the following vulnerability has been resolved: scsi: hisi_sas: Add slave_destroy interface for v3 hw WARNING is triggered when executing link reset of remote PHY and rmmod SAS driver simultaneously. Following is the WARNING log: WARNING: CPU: 61 PID: 21818 at drivers/base/core.c:1347 __device_links_no_driver+0xb4/0xc0 Call trace: __device_links_no_driver+0xb4/0xc0 device_links_driver_cleanup+0xb0/0xfc __device_release_driver+0x198/0x23c device_release_driver+0x38/0x50 bus_remove_device+0x130/0x140 device_del+0x184/0x434 __scsi_remove_device+0x118/0x150 scsi_remove_target+0x1bc/0x240 sas_rphy_remove+0x90/0x94 sas_rphy_delete+0x24/0x3c sas_destruct_devices+0x64/0xa0 [libsas] sas_revalidate_domain+0xe4/0x150 [libsas] process_one_work+0x1e0/0x46c worker_thread+0x15c/0x464 kthread+0x160/0x170 ret_from_fork+0x10/0x20 ---[ end trace 71e059eb58f85d4a ]--- During SAS phy up, link->status is set to DL_STATE_AVAILABLE in device_links_driver_bound, then this setting influences __device_links_no_driver() before driver rmmod and caused WARNING. Add the slave_destroy interface to make sure link is removed after flush workque.
CVE-2026-80637 1 Linux 1 Linux Kernel 2026-10-21 7.5 High
In the Linux kernel, the following vulnerability has been resolved: netfilter: synproxy: fix unaligned memory access in timestamp adjustment Use get_unaligned_be32() and put_unaligned_be32() to safely read and write the timestamp fields. This prevents performance degradation due to unaligned memory access or even a crash on strict alignment architectures. This follows the implementation of timestamp parsing in the networking stack at tcp_parse_options() and synproxy_parse_options().
CVE-2026-43249 1 Linux 1 Linux Kernel 2026-10-21 8.8 High
In the Linux kernel, the following vulnerability has been resolved: 9p/xen: protect xen_9pfs_front_free against concurrent calls The xenwatch thread can race with other back-end change notifications and call xen_9pfs_front_free() twice, hitting the observed general protection fault due to a double-free. Guard the teardown path so only one caller can release the front-end state at a time, preventing the crash. This is a fix for the following double-free: [ 27.052347] Oops: general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] SMP DEBUG_PAGEALLOC NOPTI [ 27.052357] CPU: 0 UID: 0 PID: 32 Comm: xenwatch Not tainted 6.18.0-02087-g51ab33fc0a8b-dirty #60 PREEMPT(none) [ 27.052363] RIP: e030:xen_9pfs_front_free+0x1d/0x150 [ 27.052368] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 41 55 41 54 55 48 89 fd 48 c7 c7 48 d0 92 85 53 e8 cb cb 05 00 48 8b 45 08 48 8b 55 00 <48> 3b 28 0f 85 f9 28 35 fe 48 3b 6a 08 0f 85 ef 28 35 fe 48 89 42 [ 27.052377] RSP: e02b:ffffc9004016fdd0 EFLAGS: 00010246 [ 27.052381] RAX: 6b6b6b6b6b6b6b6b RBX: ffff88800d66e400 RCX: 0000000000000000 [ 27.052385] RDX: 6b6b6b6b6b6b6b6b RSI: 0000000000000000 RDI: 0000000000000000 [ 27.052389] RBP: ffff88800a887040 R08: 0000000000000000 R09: 0000000000000000 [ 27.052393] R10: 0000000000000000 R11: 0000000000000000 R12: ffff888009e46b68 [ 27.052397] R13: 0000000000000200 R14: 0000000000000000 R15: ffff88800a887040 [ 27.052404] FS: 0000000000000000(0000) GS:ffff88808ca57000(0000) knlGS:0000000000000000 [ 27.052408] CS: e030 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 27.052412] CR2: 00007f9714004360 CR3: 0000000004834000 CR4: 0000000000050660 [ 27.052418] Call Trace: [ 27.052420] <TASK> [ 27.052422] xen_9pfs_front_changed+0x5d5/0x720 [ 27.052426] ? xenbus_otherend_changed+0x72/0x140 [ 27.052430] ? __pfx_xenwatch_thread+0x10/0x10 [ 27.052434] xenwatch_thread+0x94/0x1c0 [ 27.052438] ? __pfx_autoremove_wake_function+0x10/0x10 [ 27.052442] kthread+0xf8/0x240 [ 27.052445] ? __pfx_kthread+0x10/0x10 [ 27.052449] ? __pfx_kthread+0x10/0x10 [ 27.052452] ret_from_fork+0x16b/0x1a0 [ 27.052456] ? __pfx_kthread+0x10/0x10 [ 27.052459] ret_from_fork_asm+0x1a/0x30 [ 27.052463] </TASK> [ 27.052465] Modules linked in: [ 27.052471] ---[ end trace 0000000000000000 ]---
CVE-2026-43199 1 Linux 1 Linux Kernel 2026-10-21 7.5 High
In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: Fix "scheduling while atomic" in IPsec MAC address query Fix a "scheduling while atomic" bug in mlx5e_ipsec_init_macs() by replacing mlx5_query_mac_address() with ether_addr_copy() to get the local MAC address directly from netdev->dev_addr. The issue occurs because mlx5_query_mac_address() queries the hardware which involves mlx5_cmd_exec() that can sleep, but it is called from the mlx5e_ipsec_handle_event workqueue which runs in atomic context. The MAC address is already available in netdev->dev_addr, so no need to query hardware. This avoids the sleeping call and resolves the bug. Call trace: BUG: scheduling while atomic: kworker/u112:2/69344/0x00000200 __schedule+0x7ab/0xa20 schedule+0x1c/0xb0 schedule_timeout+0x6e/0xf0 __wait_for_common+0x91/0x1b0 cmd_exec+0xa85/0xff0 [mlx5_core] mlx5_cmd_exec+0x1f/0x50 [mlx5_core] mlx5_query_nic_vport_mac_address+0x7b/0xd0 [mlx5_core] mlx5_query_mac_address+0x19/0x30 [mlx5_core] mlx5e_ipsec_init_macs+0xc1/0x720 [mlx5_core] mlx5e_ipsec_build_accel_xfrm_attrs+0x422/0x670 [mlx5_core] mlx5e_ipsec_handle_event+0x2b9/0x460 [mlx5_core] process_one_work+0x178/0x2e0 worker_thread+0x2ea/0x430
CVE-2026-43126 1 Linux 1 Linux Kernel 2026-10-21 7.8 High
In the Linux kernel, the following vulnerability has been resolved: ALSA: mixer: oss: Add card disconnect checkpoints ALSA OSS mixer layer calls the kcontrol ops rather individually, and pending calls might be not always caught at disconnecting the device. For avoiding the potential UAF scenarios, add sanity checks of the card disconnection at each entry point of OSS mixer accesses. The rwsem is taken just before that check, hence the rest context should be covered by that properly.
CVE-2026-43053 1 Linux 1 Linux Kernel 2026-10-21 4.7 Medium
In the Linux kernel, the following vulnerability has been resolved: xfs: close crash window in attr dabtree inactivation When inactivating an inode with node-format extended attributes, xfs_attr3_node_inactive() invalidates all child leaf/node blocks via xfs_trans_binval(), but intentionally does not remove the corresponding entries from their parent node blocks. The implicit assumption is that xfs_attr_inactive() will truncate the entire attr fork to zero extents afterwards, so log recovery will never reach the root node and follow those stale pointers. However, if a log shutdown occurs after the leaf/node block cancellations commit but before the attr bmap truncation commits, this assumption breaks. Recovery replays the attr bmap intact (the inode still has attr fork extents), but suppresses replay of all cancelled leaf/node blocks, maybe leaving them as stale data on disk. On the next mount, xlog_recover_process_iunlinks() retries inactivation and attempts to read the root node via the attr bmap. If the root node was not replayed, reading the unreplayed root block triggers a metadata verification failure immediately; if it was replayed, following its child pointers to unreplayed child blocks triggers the same failure: XFS (pmem0): Metadata corruption detected at xfs_da3_node_read_verify+0x53/0x220, xfs_da3_node block 0x78 XFS (pmem0): Unmount and run xfs_repair XFS (pmem0): First 128 bytes of corrupted metadata buffer: 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000050: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000060: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00000070: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ XFS (pmem0): metadata I/O error in "xfs_da_read_buf+0x104/0x190" at daddr 0x78 len 8 error 117 Fix this in two places: In xfs_attr3_node_inactive(), after calling xfs_trans_binval() on a child block, immediately remove the entry that references it from the parent node in the same transaction. This eliminates the window where the parent holds a pointer to a cancelled block. Once all children are removed, the now-empty root node is converted to a leaf block within the same transaction. This node-to-leaf conversion is necessary for crash safety. If the system shutdown after the empty node is written to the log but before the second-phase bmap truncation commits, log recovery will attempt to verify the root block on disk. xfs_da3_node_verify() does not permit a node block with count == 0; such a block will fail verification and trigger a metadata corruption shutdown. on the other hand, leaf blocks are allowed to have this transient state. In xfs_attr_inactive(), split the attr fork truncation into two explicit phases. First, truncate all extents beyond the root block (the child extents whose parent references have already been removed above). Second, invalidate the root block and truncate the attr bmap to zero in a single transaction. The two operations in the second phase must be atomic: as long as the attr bmap has any non-zero length, recovery can follow it to the root block, so the root block invalidation must commit together with the bmap-to-zero truncation.
CVE-2026-43042 1 Linux 1 Linux Kernel 2026-10-21 7.1 High
In the Linux kernel, the following vulnerability has been resolved: mpls: add seqcount to protect the platform_label{,s} pair The RCU-protected codepaths (mpls_forward, mpls_dump_routes) can have an inconsistent view of platform_labels vs platform_label in case of a concurrent resize (resize_platform_label_table, under platform_mutex). This can lead to OOB accesses. This patch adds a seqcount, so that we get a consistent snapshot. Note that mpls_label_ok is also susceptible to this, so the check against RTA_DST in rtm_to_route_config, done outside platform_mutex, is not sufficient. This value gets passed to mpls_label_ok once more in both mpls_route_add and mpls_route_del, so there is no issue, but that additional check must not be removed.
CVE-2026-31767 1 Linux 1 Linux Kernel 2026-10-21 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: drm/i915/dsi: Don't do DSC horizontal timing adjustments in command mode Stop adjusting the horizontal timing values based on the compression ratio in command mode. Bspec seems to be telling us to do this only in video mode, and this is also how the Windows driver does things. This should also fix a div-by-zero on some machines because the adjusted htotal ends up being so small that we end up with line_time_us==0 when trying to determine the vtotal value in command mode. Note that this doesn't actually make the display on the Huawei Matebook E work, but at least the kernel no longer explodes when the driver loads. (cherry picked from commit 0b475e91ecc2313207196c6d7fd5c53e1a878525)
CVE-2026-31462 1 Linux 1 Linux Kernel 2026-10-21 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: drm/amdgpu: prevent immediate PASID reuse case PASID resue could cause interrupt issue when process immediately runs into hw state left by previous process exited with the same PASID, it's possible that page faults are still pending in the IH ring buffer when the process exits and frees up its PASID. To prevent the case, it uses idr cyclic allocator same as kernel pid's. (cherry picked from commit 8f1de51f49be692de137c8525106e0fce2d1912d)
CVE-2026-23361 1 Linux 1 Linux Kernel 2026-10-21 7.8 High
In the Linux kernel, the following vulnerability has been resolved: PCI: dwc: ep: Flush MSI-X write before unmapping its ATU entry Endpoint drivers use dw_pcie_ep_raise_msix_irq() to raise an MSI-X interrupt to the host using a writel(), which generates a PCI posted write transaction. There's no completion for posted writes, so the writel() may return before the PCI write completes. dw_pcie_ep_raise_msix_irq() also unmaps the outbound ATU entry used for the PCI write, so the write races with the unmap. If the PCI write loses the race with the ATU unmap, the write may corrupt host memory or cause IOMMU errors, e.g., these when running fio with a larger queue depth against nvmet-pci-epf: arm-smmu-v3 fc900000.iommu: 0x0000010000000010 arm-smmu-v3 fc900000.iommu: 0x0000020000000000 arm-smmu-v3 fc900000.iommu: 0x000000090000f040 arm-smmu-v3 fc900000.iommu: 0x0000000000000000 arm-smmu-v3 fc900000.iommu: event: F_TRANSLATION client: 0000:01:00.0 sid: 0x100 ssid: 0x0 iova: 0x90000f040 ipa: 0x0 arm-smmu-v3 fc900000.iommu: unpriv data write s1 "Input address caused fault" stag: 0x0 Flush the write by performing a readl() of the same address to ensure that the write has reached the destination before the ATU entry is unmapped. The same problem was solved for dw_pcie_ep_raise_msi_irq() in commit 8719c64e76bf ("PCI: dwc: ep: Cache MSI outbound iATU mapping"), but there it was solved by dedicating an outbound iATU only for MSI. We can't do the same for MSI-X because each vector can have a different msg_addr and the msg_addr may be changed while the vector is masked. [bhelgaas: commit log]
CVE-2026-23207 1 Linux 1 Linux Kernel 2026-10-21 4.7 Medium
In the Linux kernel, the following vulnerability has been resolved: spi: tegra210-quad: Protect curr_xfer check in IRQ handler Now that all other accesses to curr_xfer are done under the lock, protect the curr_xfer NULL check in tegra_qspi_isr_thread() with the spinlock. Without this protection, the following race can occur: CPU0 (ISR thread) CPU1 (timeout path) ---------------- ------------------- if (!tqspi->curr_xfer) // sees non-NULL spin_lock() tqspi->curr_xfer = NULL spin_unlock() handle_*_xfer() spin_lock() t = tqspi->curr_xfer // NULL! ... t->len ... // NULL dereference! With this patch, all curr_xfer accesses are now properly synchronized. Although all accesses to curr_xfer are done under the lock, in tegra_qspi_isr_thread() it checks for NULL, releases the lock and reacquires it later in handle_cpu_based_xfer()/handle_dma_based_xfer(). There is a potential for an update in between, which could cause a NULL pointer dereference. To handle this, add a NULL check inside the handlers after acquiring the lock. This ensures that if the timeout path has already cleared curr_xfer, the handler will safely return without dereferencing the NULL pointer.
CVE-2025-71285 1 Linux 1 Linux Kernel 2026-10-21 5.5 Medium
In the Linux kernel, the following vulnerability has been resolved: net: qrtr: Drop the MHI auto_queue feature for IPCR DL channels MHI stack offers the 'auto_queue' feature, which allows the MHI stack to auto queue the buffers for the RX path (DL channel). Though this feature simplifies the client driver design, it introduces race between the client drivers and the MHI stack. For instance, with auto_queue, the 'dl_callback' for the DL channel may get called before the client driver is fully probed. This means, by the time the dl_callback gets called, the client driver's structures might not be initialized, leading to NULL ptr dereference. Currently, the drivers have to workaround this issue by initializing the internal structures before calling mhi_prepare_for_transfer_autoqueue(). But even so, there is a chance that the client driver's internal code path may call the MHI queue APIs before mhi_prepare_for_transfer_autoqueue() is called, leading to similar NULL ptr dereference. This issue has been reported on the Qcom X1E80100 CRD machines affecting boot. So to properly fix all these races, drop the MHI 'auto_queue' feature altogether and let the client driver (QRTR) manage the RX buffers manually. In the QRTR driver, queue the RX buffers based on the ring length during probe and recycle the buffers in 'dl_callback' once they are consumed. This also warrants removing the setting of 'auto_queue' flag from controller drivers. Currently, this 'auto_queue' feature is only enabled for IPCR DL channel. So only the QRTR client driver requires the modification.
CVE-2025-71225 1 Linux 1 Linux Kernel 2026-10-21 5.3 Medium
In the Linux kernel, the following vulnerability has been resolved: md: suspend array while updating raid_disks via sysfs In raid1_reshape(), freeze_array() is called before modifying the r1bio memory pool (conf->r1bio_pool) and conf->raid_disks, and unfreeze_array() is called after the update is completed. However, freeze_array() only waits until nr_sync_pending and (nr_pending - nr_queued) of all buckets reaches zero. When an I/O error occurs, nr_queued is increased and the corresponding r1bio is queued to either retry_list or bio_end_io_list. As a result, freeze_array() may unblock before these r1bios are released. This can lead to a situation where conf->raid_disks and the mempool have already been updated while queued r1bios, allocated with the old raid_disks value, are later released. Consequently, free_r1bio() may access memory out of bounds in put_all_bios() and release r1bios of the wrong size to the new mempool, potentially causing issues with the mempool as well. Since only normal I/O might increase nr_queued while an I/O error occurs, suspending the array avoids this issue. Note: Updating raid_disks via ioctl SET_ARRAY_INFO already suspends the array. Therefore, we suspend the array when updating raid_disks via sysfs to avoid this issue too.
CVE-2025-71074 1 Linux 1 Linux Kernel 2026-10-21 7.8 High
In the Linux kernel, the following vulnerability has been resolved: functionfs: fix the open/removal races ffs_epfile_open() can race with removal, ending up with file->private_data pointing to freed object. There is a total count of opened files on functionfs (both ep0 and dynamic ones) and when it hits zero, dynamic files get removed. Unfortunately, that removal can happen while another thread is in ffs_epfile_open(), but has not incremented the count yet. In that case open will succeed, leaving us with UAF on any subsequent read() or write(). The root cause is that ffs->opened is misused; atomic_dec_and_test() vs. atomic_add_return() is not a good idea, when object remains visible all along. To untangle that * serialize openers on ffs->mutex (both for ep0 and for dynamic files) * have dynamic ones use atomic_inc_not_zero() and fail if we had zero ->opened; in that case the file we are opening is doomed. * have the inodes of dynamic files marked on removal (from the callback of simple_recursive_removal()) - clear ->i_private there. * have open of dynamic ones verify they hadn't been already removed, along with checking that state is FFS_ACTIVE.
CVE-2025-39927 1 Linux 1 Linux Kernel 2026-10-21 7.8 High
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. ]
CVE-2025-39754 1 Linux 1 Linux Kernel 2026-10-21 4.7 Medium
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().
CVE-2025-37906 1 Linux 1 Linux Kernel 2026-10-21 7.8 High
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.
CVE-2025-23132 1 Linux 1 Linux Kernel 2026-10-21 7 High
In the Linux kernel, the following vulnerability has been resolved: f2fs: quota: fix to avoid warning in dquot_writeback_dquots() F2FS-fs (dm-59): checkpoint=enable has some unwritten data. ------------[ cut here ]------------ WARNING: CPU: 6 PID: 8013 at fs/quota/dquot.c:691 dquot_writeback_dquots+0x2fc/0x308 pc : dquot_writeback_dquots+0x2fc/0x308 lr : f2fs_quota_sync+0xcc/0x1c4 Call trace: dquot_writeback_dquots+0x2fc/0x308 f2fs_quota_sync+0xcc/0x1c4 f2fs_write_checkpoint+0x3d4/0x9b0 f2fs_issue_checkpoint+0x1bc/0x2c0 f2fs_sync_fs+0x54/0x150 f2fs_do_sync_file+0x2f8/0x814 __f2fs_ioctl+0x1960/0x3244 f2fs_ioctl+0x54/0xe0 __arm64_sys_ioctl+0xa8/0xe4 invoke_syscall+0x58/0x114 checkpoint and f2fs_remount may race as below, resulting triggering warning in dquot_writeback_dquots(). atomic write remount - do_remount - down_write(&sb->s_umount); - f2fs_remount - ioctl - f2fs_do_sync_file - f2fs_sync_fs - f2fs_write_checkpoint - block_operations - locked = down_read_trylock(&sbi->sb->s_umount) : fail to lock due to the write lock was held by remount - up_write(&sb->s_umount); - f2fs_quota_sync - dquot_writeback_dquots - WARN_ON_ONCE(!rwsem_is_locked(&sb->s_umount)) : trigger warning because s_umount lock was unlocked by remount If checkpoint comes from mount/umount/remount/freeze/quotactl, caller of checkpoint has already held s_umount lock, calling dquot_writeback_dquots() in the context should be safe. So let's record task to sbi->umount_lock_holder, so that checkpoint can know whether the lock has held in the context or not by checking current w/ it. In addition, in order to not misrepresent caller of checkpoint, we should not allow to trigger async checkpoint for those callers: mount/umount/remount/ freeze/quotactl.
CVE-2025-22115 1 Linux 1 Linux Kernel 2026-10-21 7.8 High
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix block group refcount race in btrfs_create_pending_block_groups() Block group creation is done in two phases, which results in a slightly unintuitive property: a block group can be allocated/deallocated from after btrfs_make_block_group() adds it to the space_info with btrfs_add_bg_to_space_info(), but before creation is completely completed in btrfs_create_pending_block_groups(). As a result, it is possible for a block group to go unused and have 'btrfs_mark_bg_unused' called on it concurrently with 'btrfs_create_pending_block_groups'. This causes a number of issues, which were fixed with the block group flag 'BLOCK_GROUP_FLAG_NEW'. However, this fix is not quite complete. Since it does not use the unused_bg_lock, it is possible for the following race to occur: btrfs_create_pending_block_groups btrfs_mark_bg_unused if list_empty // false list_del_init clear_bit else if (test_bit) // true list_move_tail And we get into the exact same broken ref count and invalid new_bgs state for transaction cleanup that BLOCK_GROUP_FLAG_NEW was designed to prevent. The broken refcount aspect will result in a warning like: [1272.943527] refcount_t: underflow; use-after-free. [1272.943967] WARNING: CPU: 1 PID: 61 at lib/refcount.c:28 refcount_warn_saturate+0xba/0x110 [1272.944731] Modules linked in: btrfs virtio_net xor zstd_compress raid6_pq null_blk [last unloaded: btrfs] [1272.945550] CPU: 1 UID: 0 PID: 61 Comm: kworker/u32:1 Kdump: loaded Tainted: G W 6.14.0-rc5+ #108 [1272.946368] Tainted: [W]=WARN [1272.946585] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014 [1272.947273] Workqueue: btrfs_discard btrfs_discard_workfn [btrfs] [1272.947788] RIP: 0010:refcount_warn_saturate+0xba/0x110 [1272.949532] RSP: 0018:ffffbf1200247df0 EFLAGS: 00010282 [1272.949901] RAX: 0000000000000000 RBX: ffffa14b00e3f800 RCX: 0000000000000000 [1272.950437] RDX: 0000000000000000 RSI: ffffbf1200247c78 RDI: 00000000ffffdfff [1272.950986] RBP: ffffa14b00dc2860 R08: 00000000ffffdfff R09: ffffffff90526268 [1272.951512] R10: ffffffff904762c0 R11: 0000000063666572 R12: ffffa14b00dc28c0 [1272.952024] R13: 0000000000000000 R14: ffffa14b00dc2868 R15: 000001285dcd12c0 [1272.952850] FS: 0000000000000000(0000) GS:ffffa14d33c40000(0000) knlGS:0000000000000000 [1272.953458] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [1272.953931] CR2: 00007f838cbda000 CR3: 000000010104e000 CR4: 00000000000006f0 [1272.954474] Call Trace: [1272.954655] <TASK> [1272.954812] ? refcount_warn_saturate+0xba/0x110 [1272.955173] ? __warn.cold+0x93/0xd7 [1272.955487] ? refcount_warn_saturate+0xba/0x110 [1272.955816] ? report_bug+0xe7/0x120 [1272.956103] ? handle_bug+0x53/0x90 [1272.956424] ? exc_invalid_op+0x13/0x60 [1272.956700] ? asm_exc_invalid_op+0x16/0x20 [1272.957011] ? refcount_warn_saturate+0xba/0x110 [1272.957399] btrfs_discard_cancel_work.cold+0x26/0x2b [btrfs] [1272.957853] btrfs_put_block_group.cold+0x5d/0x8e [btrfs] [1272.958289] btrfs_discard_workfn+0x194/0x380 [btrfs] [1272.958729] process_one_work+0x130/0x290 [1272.959026] worker_thread+0x2ea/0x420 [1272.959335] ? __pfx_worker_thread+0x10/0x10 [1272.959644] kthread+0xd7/0x1c0 [1272.959872] ? __pfx_kthread+0x10/0x10 [1272.960172] ret_from_fork+0x30/0x50 [1272.960474] ? __pfx_kthread+0x10/0x10 [1272.960745] ret_from_fork_asm+0x1a/0x30 [1272.961035] </TASK> [1272.961238] ---[ end trace 0000000000000000 ]--- Though we have seen them in the async discard workfn as well. It is most likely to happen after a relocation finishes which cancels discard, tears down the block group, etc. Fix this fully by taking the lock arou ---truncated---