{"cve":"CVE-2025-38358","nvd":{"published":"2025-07-25T13:15:24.573","modified":"2026-06-17T09:16:42.003","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix race between async reclaim worker and close_ctree()\n\nSyzbot reported an assertion failure due to an attempt to add a delayed\niput after we have set BTRFS_FS_STATE_NO_DELAYED_IPUT in the fs_info\nstate:\n\n  WARNING: CPU: 0 PID: 65 at fs/btrfs/inode.c:3420 btrfs_add_delayed_iput+0x2f8/0x370 fs/btrfs/inode.c:3420\n  Modules linked in:\n  CPU: 0 UID: 0 PID: 65 Comm: kworker/u8:4 Not tainted 6.15.0-next-20250530-syzkaller #0 PREEMPT(full)\n  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025\n  Workqueue: btrfs-endio-write btrfs_work_helper\n  RIP: 0010:btrfs_add_delayed_iput+0x2f8/0x370 fs/btrfs/inode.c:3420\n  Code: 4e ad 5d (...)\n  RSP: 0018:ffffc9000213f780 EFLAGS: 00010293\n  RAX: ffffffff83c635b7 RBX: ffff888058920000 RCX: ffff88801c769e00\n  RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000000\n  RBP: 0000000000000001 R08: ffff888058921b67 R09: 1ffff1100b12436c\n  R10: dffffc0000000000 R11: ffffed100b12436d R12: 0000000000000001\n  R13: dffffc0000000000 R14: ffff88807d748000 R15: 0000000000000100\n  FS:  0000000000000000(0000) GS:ffff888125c53000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 00002000000bd038 CR3: 000000006a142000 CR4: 00000000003526f0\n  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\n  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\n  Call Trace:\n   <TASK>\n   btrfs_put_ordered_extent+0x19f/0x470 fs/btrfs/ordered-data.c:635\n   btrfs_finish_one_ordered+0x11d8/0x1b10 fs/btrfs/inode.c:3312\n   btrfs_work_helper+0x399/0xc20 fs/btrfs/async-thread.c:312\n   process_one_work kernel/workqueue.c:3238 [inline]\n   process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321\n   worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402\n   kthread+0x70e/0x8a0 kernel/kthread.c:464\n   ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148\n   ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245\n   </TASK>\n\nThis can happen due to a race with the async reclaim worker like this:\n\n1) The async metadata reclaim worker enters shrink_delalloc(), which calls\n   btrfs_start_delalloc_roots() with an nr_pages argument that has a value\n   less than LONG_MAX, and that in turn enters start_delalloc_inodes(),\n   which sets the local variable 'full_flush' to false because\n   wbc->nr_to_write is less than LONG_MAX;\n\n2) There it finds inode X in a root's delalloc list, grabs a reference for\n   inode X (with igrab()), and triggers writeback for it with\n   filemap_fdatawrite_wbc(), which creates an ordered extent for inode X;\n\n3) The unmount sequence starts from another task, we enter close_ctree()\n   and we flush the workqueue fs_info->endio_write_workers, which waits\n   for the ordered extent for inode X to complete and when dropping the\n   last reference of the ordered extent, with btrfs_put_ordered_extent(),\n   when we call btrfs_add_delayed_iput() we don't add the inode to the\n   list of delayed iputs because it has a refcount of 2, so we decrement\n   it to 1 and return;\n\n4) Shortly after at close_ctree() we call btrfs_run_delayed_iputs() which\n   runs all delayed iputs, and then we set BTRFS_FS_STATE_NO_DELAYED_IPUT\n   in the fs_info state;\n\n5) The async reclaim worker, after calling filemap_fdatawrite_wbc(), now\n   calls btrfs_add_delayed_iput() for inode X and there we trigger an\n   assertion failure since the fs_info state has the flag\n   BTRFS_FS_STATE_NO_DELAYED_IPUT set.\n\nFix this by setting BTRFS_FS_STATE_NO_DELAYED_IPUT only after we wait for\nthe async reclaim workers to finish, after we call cancel_work_sync() for\nthem at close_ctree(), and by running delayed iputs after wait for the\nreclaim workers to finish and before setting the bit.\n\nThis race was recently introduced by commit 19e60b2a95f5 (\"btrfs: add\nextra warning if delayed iput is added when it's not allowed\"). Without\nthe new validation at btrfs_add_delayed_iput(), \n---truncated---","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","score":4.7},"cwes":["CWE-362"],"references":["https://git.kernel.org/stable/c/4693cda2c06039c875f2eef0123b22340c34bfa0","https://git.kernel.org/stable/c/a26bf338cdad3643a6e7c3d78a172baadba15c1a"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:05:46.678065081+00:00"},"epss":{"cve":"CVE-2025-38358","score":0.00112,"percentile":0.01356,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}