In the Linux kernel, the following vulnerability has been resolved:
btrfs: fix race between async reclaim worker and close_ctree()
Syzbot reported an assertion failure due to an attempt to add a delayed iput after we have set BTRFS_FS_STATE_NO_DELAYED_IPUT in the fs_info state:
WARNING: CPU: 0 PID: 65 at fs/btrfs/inode.c:3420 btrfs_add_delayed_iput+0x2f8/0x370 fs/btrfs/inode.c:3420 Modules linked in: CPU: 0 UID: 0 PID: 65 Comm: kworker/u8:4 Not tainted 6.15.0-next-20250530-syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Workqueue: btrfs-endio-write btrfs_work_helper RIP: 0010:btrfs_add_delayed_iput+0x2f8/0x370 fs/btrfs/inode.c:3420 Code: 4e ad 5d (…) RSP: 0018:ffffc9000213f780 EFLAGS: 00010293 RAX: ffffffff83c635b7 RBX: ffff888058920000 RCX: ffff88801c769e00 RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000000 RBP: 0000000000000001 R08: ffff888058921b67 R09: 1ffff1100b12436c R10: dffffc0000000000 R11: ffffed100b12436d R12: 0000000000000001 R13: dffffc0000000000 R14: ffff88807d748000 R15: 0000000000000100 FS: 0000000000000000(0000) GS:ffff888125c53000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00002000000bd038 CR3: 000000006a142000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: btrfs_put_ordered_extent+0x19f/0x470 fs/btrfs/ordered-data.c:635 btrfs_finish_one_ordered+0x11d8/0x1b10 fs/btrfs/inode.c:3312 btrfs_work_helper+0x399/0xc20 fs/btrfs/async-thread.c:312 process_one_work kernel/workqueue.c:3238 [inline] process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402 kthread+0x70e/0x8a0 kernel/kthread.c:464 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
This can happen due to a race with the async reclaim worker like this:
The async metadata reclaim worker enters shrink_delalloc(), which calls btrfs_start_delalloc_roots() with an nr_pages argument that has a value less than LONG_MAX, and that in turn enters start_delalloc_inodes(), which sets the local variable full_flush to false because wbc->nr_to_write is less than LONG_MAX;
There it finds inode X in a roots delalloc list, grabs a reference for inode X (with igrab()), and triggers writeback for it with filemap_fdatawrite_wbc(), which creates an ordered extent for inode X;
The unmount sequence starts from another task, we enter close_ctree() and we flush the workqueue fs_info->endio_write_workers, which waits for the ordered extent for inode X to complete and when dropping the last reference of the ordered extent, with btrfs_put_ordered_extent(), when we call btrfs_add_delayed_iput() we dont add the inode to the list of delayed iputs because it has a refcount of 2, so we decrement it to 1 and return;
Shortly after at close_ctree() we call btrfs_run_delayed_iputs() which runs all delayed iputs, and then we set BTRFS_FS_STATE_NO_DELAYED_IPUT in the fs_info state;
The async reclaim worker, after calling filemap_fdatawrite_wbc(), now calls btrfs_add_delayed_iput() for inode X and there we trigger an assertion failure since the fs_info state has the flag BTRFS_FS_STATE_NO_DELAYED_IPUT set.
Fix this by setting BTRFS_FS_STATE_NO_DELAYED_IPUT only after we wait for the async reclaim workers to finish, after we call cancel_work_sync() for them at close_ctree(), and by running delayed iputs after wait for the reclaim workers to finish and before setting the bit.
This race was recently introduced by commit 19e60b2a95f5 (btrfs: add extra warning if delayed iput is added when its not allowed). Without the new validation at btrfs_add_delayed_iput(), —truncated—
Name | Vendor | Start Version | End Version |
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Linux | Ubuntu | devel | * |
Linux-allwinner-5.19 | Ubuntu | jammy | * |
Linux-allwinner-5.19 | Ubuntu | upstream | * |
Linux-aws | Ubuntu | upstream | * |
Linux-aws-5.0 | Ubuntu | bionic | * |
Linux-aws-5.0 | Ubuntu | esm-infra/bionic | * |
Linux-aws-5.0 | Ubuntu | upstream | * |
Linux-aws-5.11 | Ubuntu | esm-infra/focal | * |
Linux-aws-5.11 | Ubuntu | focal | * |
Linux-aws-5.11 | Ubuntu | upstream | * |
Linux-aws-5.13 | Ubuntu | esm-infra/focal | * |
Linux-aws-5.13 | Ubuntu | focal | * |
Linux-aws-5.13 | Ubuntu | upstream | * |
Linux-aws-5.15 | Ubuntu | upstream | * |
Linux-aws-5.19 | Ubuntu | jammy | * |
Linux-aws-5.19 | Ubuntu | upstream | * |
Linux-aws-5.3 | Ubuntu | bionic | * |
Linux-aws-5.3 | Ubuntu | esm-infra/bionic | * |
Linux-aws-5.3 | Ubuntu | upstream | * |
Linux-aws-5.4 | Ubuntu | upstream | * |
Linux-aws-5.8 | Ubuntu | esm-infra/focal | * |
Linux-aws-5.8 | Ubuntu | focal | * |
Linux-aws-5.8 | Ubuntu | upstream | * |
Linux-aws-6.14 | Ubuntu | upstream | * |
Linux-aws-6.2 | Ubuntu | jammy | * |
Linux-aws-6.2 | Ubuntu | upstream | * |
Linux-aws-6.5 | Ubuntu | jammy | * |
Linux-aws-6.5 | Ubuntu | upstream | * |
Linux-aws-6.8 | Ubuntu | upstream | * |
Linux-aws-fips | Ubuntu | trusty | * |
Linux-aws-fips | Ubuntu | upstream | * |
Linux-aws-fips | Ubuntu | xenial | * |
Linux-aws-hwe | Ubuntu | upstream | * |
Linux-azure | Ubuntu | bionic | * |
Linux-azure | Ubuntu | esm-infra/bionic | * |
Linux-azure | Ubuntu | upstream | * |
Linux-azure-4.15 | Ubuntu | upstream | * |
Linux-azure-5.11 | Ubuntu | esm-infra/focal | * |
Linux-azure-5.11 | Ubuntu | focal | * |
Linux-azure-5.11 | Ubuntu | upstream | * |
Linux-azure-5.13 | Ubuntu | esm-infra/focal | * |
Linux-azure-5.13 | Ubuntu | focal | * |
Linux-azure-5.13 | Ubuntu | upstream | * |
Linux-azure-5.15 | Ubuntu | upstream | * |
Linux-azure-5.19 | Ubuntu | jammy | * |
Linux-azure-5.19 | Ubuntu | upstream | * |
Linux-azure-5.3 | Ubuntu | bionic | * |
Linux-azure-5.3 | Ubuntu | esm-infra/bionic | * |
Linux-azure-5.3 | Ubuntu | upstream | * |
Linux-azure-5.4 | Ubuntu | upstream | * |
Linux-azure-5.8 | Ubuntu | esm-infra/focal | * |
Linux-azure-5.8 | Ubuntu | focal | * |
Linux-azure-5.8 | Ubuntu | upstream | * |
Linux-azure-6.11 | Ubuntu | noble | * |
Linux-azure-6.11 | Ubuntu | upstream | * |
Linux-azure-6.2 | Ubuntu | jammy | * |
Linux-azure-6.2 | Ubuntu | upstream | * |
Linux-azure-6.5 | Ubuntu | jammy | * |
Linux-azure-6.5 | Ubuntu | upstream | * |
Linux-azure-6.8 | Ubuntu | upstream | * |
Linux-azure-edge | Ubuntu | bionic | * |
Linux-azure-edge | Ubuntu | esm-infra/bionic | * |
Linux-azure-edge | Ubuntu | upstream | * |
Linux-azure-fde | Ubuntu | esm-infra/focal | * |
Linux-azure-fde | Ubuntu | focal | * |
Linux-azure-fde | Ubuntu | upstream | * |
Linux-azure-fde-5.15 | Ubuntu | upstream | * |
Linux-azure-fde-5.19 | Ubuntu | jammy | * |
Linux-azure-fde-5.19 | Ubuntu | upstream | * |
Linux-azure-fde-6.2 | Ubuntu | jammy | * |
Linux-azure-fde-6.2 | Ubuntu | upstream | * |
Linux-azure-fips | Ubuntu | trusty | * |
Linux-azure-fips | Ubuntu | upstream | * |
Linux-azure-fips | Ubuntu | xenial | * |
Linux-azure-nvidia | Ubuntu | upstream | * |
Linux-bluefield | Ubuntu | upstream | * |
Linux-fips | Ubuntu | upstream | * |
Linux-gcp | Ubuntu | bionic | * |
Linux-gcp | Ubuntu | esm-infra/bionic | * |
Linux-gcp | Ubuntu | upstream | * |
Linux-gcp-4.15 | Ubuntu | upstream | * |
Linux-gcp-5.11 | Ubuntu | esm-infra/focal | * |
Linux-gcp-5.11 | Ubuntu | focal | * |
Linux-gcp-5.11 | Ubuntu | upstream | * |
Linux-gcp-5.13 | Ubuntu | esm-infra/focal | * |
Linux-gcp-5.13 | Ubuntu | focal | * |
Linux-gcp-5.13 | Ubuntu | upstream | * |
Linux-gcp-5.15 | Ubuntu | upstream | * |
Linux-gcp-5.19 | Ubuntu | jammy | * |
Linux-gcp-5.19 | Ubuntu | upstream | * |
Linux-gcp-5.3 | Ubuntu | bionic | * |
Linux-gcp-5.3 | Ubuntu | esm-infra/bionic | * |
Linux-gcp-5.3 | Ubuntu | upstream | * |
Linux-gcp-5.4 | Ubuntu | upstream | * |
Linux-gcp-5.8 | Ubuntu | esm-infra/focal | * |
Linux-gcp-5.8 | Ubuntu | focal | * |
Linux-gcp-5.8 | Ubuntu | upstream | * |
Linux-gcp-6.11 | Ubuntu | noble | * |
Linux-gcp-6.11 | Ubuntu | upstream | * |
Linux-gcp-6.14 | Ubuntu | upstream | * |
Linux-gcp-6.2 | Ubuntu | jammy | * |
Linux-gcp-6.2 | Ubuntu | upstream | * |
Linux-gcp-6.5 | Ubuntu | jammy | * |
Linux-gcp-6.5 | Ubuntu | upstream | * |
Linux-gcp-6.8 | Ubuntu | upstream | * |
Linux-gcp-fips | Ubuntu | trusty | * |
Linux-gcp-fips | Ubuntu | upstream | * |
Linux-gcp-fips | Ubuntu | xenial | * |
Linux-gke | Ubuntu | esm-infra/focal | * |
Linux-gke | Ubuntu | focal | * |
Linux-gke | Ubuntu | upstream | * |
Linux-gke | Ubuntu | xenial | * |
Linux-gke-4.15 | Ubuntu | bionic | * |
Linux-gke-4.15 | Ubuntu | esm-infra/bionic | * |
Linux-gke-4.15 | Ubuntu | upstream | * |
Linux-gke-5.15 | Ubuntu | esm-infra/focal | * |
Linux-gke-5.15 | Ubuntu | focal | * |
Linux-gke-5.15 | Ubuntu | upstream | * |
Linux-gke-5.4 | Ubuntu | bionic | * |
Linux-gke-5.4 | Ubuntu | esm-infra/bionic | * |
Linux-gke-5.4 | Ubuntu | upstream | * |
Linux-gkeop | Ubuntu | esm-infra/focal | * |
Linux-gkeop | Ubuntu | focal | * |
Linux-gkeop | Ubuntu | upstream | * |
Linux-gkeop-5.15 | Ubuntu | esm-infra/focal | * |
Linux-gkeop-5.15 | Ubuntu | focal | * |
Linux-gkeop-5.15 | Ubuntu | upstream | * |
Linux-gkeop-5.4 | Ubuntu | bionic | * |
Linux-gkeop-5.4 | Ubuntu | esm-infra/bionic | * |
Linux-gkeop-5.4 | Ubuntu | upstream | * |
Linux-hwe | Ubuntu | bionic | * |
Linux-hwe | Ubuntu | esm-infra/bionic | * |
Linux-hwe | Ubuntu | upstream | * |
Linux-hwe-5.11 | Ubuntu | esm-infra/focal | * |
Linux-hwe-5.11 | Ubuntu | focal | * |
Linux-hwe-5.11 | Ubuntu | upstream | * |
Linux-hwe-5.13 | Ubuntu | esm-infra/focal | * |
Linux-hwe-5.13 | Ubuntu | focal | * |
Linux-hwe-5.13 | Ubuntu | upstream | * |
Linux-hwe-5.15 | Ubuntu | upstream | * |
Linux-hwe-5.19 | Ubuntu | jammy | * |
Linux-hwe-5.19 | Ubuntu | upstream | * |
Linux-hwe-5.4 | Ubuntu | upstream | * |
Linux-hwe-5.8 | Ubuntu | esm-infra/focal | * |
Linux-hwe-5.8 | Ubuntu | focal | * |
Linux-hwe-5.8 | Ubuntu | upstream | * |
Linux-hwe-6.11 | Ubuntu | noble | * |
Linux-hwe-6.11 | Ubuntu | upstream | * |
Linux-hwe-6.14 | Ubuntu | upstream | * |
Linux-hwe-6.2 | Ubuntu | jammy | * |
Linux-hwe-6.2 | Ubuntu | upstream | * |
Linux-hwe-6.5 | Ubuntu | jammy | * |
Linux-hwe-6.5 | Ubuntu | upstream | * |
Linux-hwe-6.8 | Ubuntu | upstream | * |
Linux-hwe-edge | Ubuntu | bionic | * |
Linux-hwe-edge | Ubuntu | esm-infra/bionic | * |
Linux-hwe-edge | Ubuntu | esm-infra/xenial | * |
Linux-hwe-edge | Ubuntu | upstream | * |
Linux-hwe-edge | Ubuntu | xenial | * |
Linux-ibm | Ubuntu | upstream | * |
Linux-ibm-5.15 | Ubuntu | upstream | * |
Linux-ibm-5.4 | Ubuntu | upstream | * |
Linux-ibm-6.8 | Ubuntu | upstream | * |
Linux-intel | Ubuntu | upstream | * |
Linux-intel-5.13 | Ubuntu | esm-infra/focal | * |
Linux-intel-5.13 | Ubuntu | focal | * |
Linux-intel-5.13 | Ubuntu | upstream | * |
Linux-intel-iot-realtime | Ubuntu | jammy | * |
Linux-intel-iot-realtime | Ubuntu | upstream | * |
Linux-intel-iotg | Ubuntu | upstream | * |
Linux-intel-iotg-5.15 | Ubuntu | upstream | * |
Linux-iot | Ubuntu | upstream | * |
Linux-kvm | Ubuntu | upstream | * |
Linux-lowlatency | Ubuntu | upstream | * |
Linux-lowlatency-hwe-5.15 | Ubuntu | upstream | * |
Linux-lowlatency-hwe-5.19 | Ubuntu | jammy | * |
Linux-lowlatency-hwe-5.19 | Ubuntu | upstream | * |
Linux-lowlatency-hwe-6.11 | Ubuntu | noble | * |
Linux-lowlatency-hwe-6.11 | Ubuntu | upstream | * |
Linux-lowlatency-hwe-6.2 | Ubuntu | jammy | * |
Linux-lowlatency-hwe-6.2 | Ubuntu | upstream | * |
Linux-lowlatency-hwe-6.5 | Ubuntu | jammy | * |
Linux-lowlatency-hwe-6.5 | Ubuntu | upstream | * |
Linux-lowlatency-hwe-6.8 | Ubuntu | upstream | * |
Linux-lts-xenial | Ubuntu | upstream | * |
Linux-nvidia | Ubuntu | upstream | * |
Linux-nvidia-6.11 | Ubuntu | upstream | * |
Linux-nvidia-6.2 | Ubuntu | jammy | * |
Linux-nvidia-6.2 | Ubuntu | upstream | * |
Linux-nvidia-6.5 | Ubuntu | jammy | * |
Linux-nvidia-6.5 | Ubuntu | upstream | * |
Linux-nvidia-6.8 | Ubuntu | upstream | * |
Linux-nvidia-lowlatency | Ubuntu | upstream | * |
Linux-nvidia-tegra | Ubuntu | upstream | * |
Linux-nvidia-tegra-5.15 | Ubuntu | upstream | * |
Linux-nvidia-tegra-igx | Ubuntu | upstream | * |
Linux-oem | Ubuntu | bionic | * |
Linux-oem | Ubuntu | esm-infra/bionic | * |
Linux-oem | Ubuntu | upstream | * |
Linux-oem | Ubuntu | xenial | * |
Linux-oem-5.10 | Ubuntu | esm-infra/focal | * |
Linux-oem-5.10 | Ubuntu | focal | * |
Linux-oem-5.10 | Ubuntu | upstream | * |
Linux-oem-5.13 | Ubuntu | esm-infra/focal | * |
Linux-oem-5.13 | Ubuntu | focal | * |
Linux-oem-5.13 | Ubuntu | upstream | * |
Linux-oem-5.14 | Ubuntu | esm-infra/focal | * |
Linux-oem-5.14 | Ubuntu | focal | * |
Linux-oem-5.14 | Ubuntu | upstream | * |
Linux-oem-5.17 | Ubuntu | jammy | * |
Linux-oem-5.17 | Ubuntu | upstream | * |
Linux-oem-5.6 | Ubuntu | esm-infra/focal | * |
Linux-oem-5.6 | Ubuntu | focal | * |
Linux-oem-5.6 | Ubuntu | upstream | * |
Linux-oem-6.0 | Ubuntu | jammy | * |
Linux-oem-6.0 | Ubuntu | upstream | * |
Linux-oem-6.1 | Ubuntu | jammy | * |
Linux-oem-6.1 | Ubuntu | upstream | * |
Linux-oem-6.11 | Ubuntu | upstream | * |
Linux-oem-6.14 | Ubuntu | upstream | * |
Linux-oem-6.5 | Ubuntu | jammy | * |
Linux-oem-6.5 | Ubuntu | upstream | * |
Linux-oem-6.8 | Ubuntu | upstream | * |
Linux-oracle | Ubuntu | upstream | * |
Linux-oracle-5.0 | Ubuntu | bionic | * |
Linux-oracle-5.0 | Ubuntu | esm-infra/bionic | * |
Linux-oracle-5.0 | Ubuntu | upstream | * |
Linux-oracle-5.11 | Ubuntu | esm-infra/focal | * |
Linux-oracle-5.11 | Ubuntu | focal | * |
Linux-oracle-5.11 | Ubuntu | upstream | * |
Linux-oracle-5.13 | Ubuntu | esm-infra/focal | * |
Linux-oracle-5.13 | Ubuntu | focal | * |
Linux-oracle-5.13 | Ubuntu | upstream | * |
Linux-oracle-5.15 | Ubuntu | upstream | * |
Linux-oracle-5.3 | Ubuntu | bionic | * |
Linux-oracle-5.3 | Ubuntu | esm-infra/bionic | * |
Linux-oracle-5.3 | Ubuntu | upstream | * |
Linux-oracle-5.4 | Ubuntu | upstream | * |
Linux-oracle-5.8 | Ubuntu | esm-infra/focal | * |
Linux-oracle-5.8 | Ubuntu | focal | * |
Linux-oracle-5.8 | Ubuntu | upstream | * |
Linux-oracle-6.14 | Ubuntu | upstream | * |
Linux-oracle-6.5 | Ubuntu | jammy | * |
Linux-oracle-6.5 | Ubuntu | upstream | * |
Linux-oracle-6.8 | Ubuntu | upstream | * |
Linux-raspi | Ubuntu | upstream | * |
Linux-raspi-5.4 | Ubuntu | upstream | * |
Linux-raspi-realtime | Ubuntu | noble | * |
Linux-raspi-realtime | Ubuntu | upstream | * |
Linux-raspi2 | Ubuntu | bionic | * |
Linux-raspi2 | Ubuntu | esm-infra/focal | * |
Linux-raspi2 | Ubuntu | focal | * |
Linux-raspi2 | Ubuntu | upstream | * |
Linux-raspi2 | Ubuntu | xenial | * |
Linux-realtime | Ubuntu | jammy | * |
Linux-realtime | Ubuntu | noble | * |
Linux-realtime | Ubuntu | upstream | * |
Linux-riscv | Ubuntu | esm-infra/focal | * |
Linux-riscv | Ubuntu | focal | * |
Linux-riscv | Ubuntu | jammy | * |
Linux-riscv | Ubuntu | noble | * |
Linux-riscv | Ubuntu | upstream | * |
Linux-riscv-5.11 | Ubuntu | esm-infra/focal | * |
Linux-riscv-5.11 | Ubuntu | focal | * |
Linux-riscv-5.11 | Ubuntu | upstream | * |
Linux-riscv-5.15 | Ubuntu | upstream | * |
Linux-riscv-5.19 | Ubuntu | jammy | * |
Linux-riscv-5.19 | Ubuntu | upstream | * |
Linux-riscv-5.8 | Ubuntu | esm-infra/focal | * |
Linux-riscv-5.8 | Ubuntu | focal | * |
Linux-riscv-5.8 | Ubuntu | upstream | * |
Linux-riscv-6.14 | Ubuntu | upstream | * |
Linux-riscv-6.5 | Ubuntu | jammy | * |
Linux-riscv-6.5 | Ubuntu | upstream | * |
Linux-riscv-6.8 | Ubuntu | upstream | * |
Linux-starfive-5.19 | Ubuntu | jammy | * |
Linux-starfive-5.19 | Ubuntu | upstream | * |
Linux-starfive-6.2 | Ubuntu | jammy | * |
Linux-starfive-6.2 | Ubuntu | upstream | * |
Linux-starfive-6.5 | Ubuntu | jammy | * |
Linux-starfive-6.5 | Ubuntu | upstream | * |
Linux-xilinx-zynqmp | Ubuntu | upstream | * |