CVE-2023-53829

None

CVSS

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EPSS

0.2%

Published

Dec 9, 2025

CISA due date

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Cloudanix analysis

Schedule a fix SSVC: Track

A bug in the Linux filesystem code can cause the whole computer to crash when certain file operations are interrupted.

Exploitation: Local Privilege
Attacker needs: Local User
Complexity: Moderate
Impact: Denial Of Service
Component: OS kernel
Class: Race Condition
Remediation: Upgrade
Effort: Medium
Patch risk: Low

What it actually does

Aborting an atomic write in f2fs leaves a dirty inode flag set; during subsequent inode eviction the f2fs_bug_on check in f2fs_evict_inode fires, producing a kernel panic.

Why it matters to the business

Systems using the f2fs filesystem can experience unexpected kernel crashes and reboots when atomic file operations are aborted, leading to service disruption and potential data loss on affected volumes.

How an attack unfolds

An attacker with local access triggers an atomic write followed by an abort condition on an f2fs filesystem; the resulting stale dirty inode causes the kernel to hit the BUG assertion during normal inode eviction triggered by unmount or process exit.

How to fix it

Upgrade affected kernels to a version containing the fix that flushes the inode on atomic-write abort. For the listed Ubuntu salt packages apply the exact fixed versions: 0.17.5+ds-1ubuntu0.1~esm2 on 14.04, 2015.8.8+ds-1ubuntu0.1 on 16.04, and 2017.7.4+dfsg1-1ubuntu18.04.2 on 18.04.

How to confirm the fix worked

Confirm the running kernel contains the inode-flush change in f2fs_abort_atomic_write and that f2fs_bug_on is no longer reachable on abort+evict paths; test by reproducing the syzbot reproducer sequence without triggering the BUG.

Typical attack path

Obtain local code execution on a system with an f2fs filesystem
Open a file and begin an atomic write operation
Abort the atomic write
Trigger inode eviction through process exit or filesystem unmount
Observe kernel BUG and panic

How to detect it

Search kernel logs for 'kernel BUG at fs/f2fs/inode.c' and 'f2fs_bug_on' messages; correlate with f2fs mount events and process exits that perform atomic writes.

What your security team should do

Prioritize kernel upgrades on all systems using f2fs
Apply the precise salt package fixes listed for each Ubuntu release
Monitor for f2fs-related kernel panics in system logs until patched
Limit untrusted local code execution on f2fs volumes while unpatched

The record

In the Linux kernel, the following vulnerability has been resolved: f2fs: flush inode if atomic file is aborted Let's flush the inode being aborted atomic operation to avoid stale dirty inode during eviction in this call stack: f2fs_mark_inode_dirty_sync+0x22/0x40 [f2fs] f2fs_abort_atomic_write+0xc4/0xf0 [f2fs] f2fs_evict_inode+0x3f/0x690 [f2fs] ? sugov_start+0x140/0x140 evict+0xc3/0x1c0 evict_inodes+0x17b/0x210 generic_shutdown_super+0x32/0x120 kill_block_super+0x21/0x50 deactivate_locked_super+0x31/0x90 cleanup_mnt+0x100/0x160 task_work_run+0x59/0x90 do_exit+0x33b/0xa50 do_group_exit+0x2d/0x80 __x64_sys_exit_group+0x14/0x20 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd This triggers f2fs_bug_on() in f2fs_evict_inode: f2fs_bug_on(sbi, is_inode_flag_set(inode, FI_DIRTY_INODE)); This fixes the syzbot report: loop0: detected capacity change from 0 to 131072 F2FS-fs (loop0): invalid crc value F2FS-fs (loop0): Found nat_bits in checkpoint F2FS-fs (loop0): Mounted with checkpoint version = 48b305e4 ------------[ cut here ]------------ kernel BUG at fs/f2fs/inode.c:869! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 5014 Comm: syz-executor220 Not tainted 6.4.0-syzkaller-11479-g6cd06ab12d1a #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023 RIP: 0010:f2fs_evict_inode+0x172d/0x1e00 fs/f2fs/inode.c:869 Code: ff df 48 c1 ea 03 80 3c 02 00 0f 85 6a 06 00 00 8b 75 40 ba 01 00 00 00 4c 89 e7 e8 6d ce 06 00 e9 aa fc ff ff e8 63 22 e2 fd <0f> 0b e8 5c 22 e2 fd 48 c7 c0 a8 3a 18 8d 48 ba 00 00 00 00 00 fc RSP: 0018:ffffc90003a6fa00 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0000000000000000 RDX: ffff8880273b8000 RSI: ffffffff83a2bd0d RDI: 0000000000000007 RBP: ffff888077db91b0 R08: 0000000000000007 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: ffff888029a3c000 R13: ffff888077db9660 R14: ffff888029a3c0b8 R15: ffff888077db9c50 FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f1909bb9000 CR3: 00000000276a9000 CR4: 0000000000350ef0 Call Trace: <TASK> evict+0x2ed/0x6b0 fs/inode.c:665 dispose_list+0x117/0x1e0 fs/inode.c:698 evict_inodes+0x345/0x440 fs/inode.c:748 generic_shutdown_super+0xaf/0x480 fs/super.c:478 kill_block_super+0x64/0xb0 fs/super.c:1417 kill_f2fs_super+0x2af/0x3c0 fs/f2fs/super.c:4704 deactivate_locked_super+0x98/0x160 fs/super.c:330 deactivate_super+0xb1/0xd0 fs/super.c:361 cleanup_mnt+0x2ae/0x3d0 fs/namespace.c:1254 task_work_run+0x16f/0x270 kernel/task_work.c:179 exit_task_work include/linux/task_work.h:38 [inline] do_exit+0xa9a/0x29a0 kernel/exit.c:874 do_group_exit+0xd4/0x2a0 kernel/exit.c:1024 __do_sys_exit_group kernel/exit.c:1035 [inline] __se_sys_exit_group kernel/exit.c:1033 [inline] __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1033 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f309be71a09 Code: Unable to access opcode bytes at 0x7f309be719df. RSP: 002b:00007fff171df518 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007f309bef7330 RCX: 00007f309be71a09 RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000001 RBP: 0000000000000001 R08: ffffffffffffffc0 R09: 00007f309bef1e40 R10: 0000000000010600 R11: 0000000000000246 R12: 00007f309bef7330 R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000001 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:f2fs_evict_inode+0x172d/0x1e00 fs/f2fs/inode.c:869 Code: ff df 48 c1 ea 03 80 3c 02 00 0f 85 6a 06 00 00 8b 75 40 ba 01 00 00 00 4c 89 e7 e8 6d ce 06 00 e9 aa fc ff ff e8 63 22 e2 fd <0f> 0b e8 5c 22 e2 fd 48 c7 c0 a8 3a 18 8d 48 ba 00 00 00 00 00 fc RSP: 0018:ffffc90003a6fa00 EFLAGS: 00010293 RAX: 0000000000000000 RBX: 0000000000 ---truncated---

Affected packages

Ecosystem	Package	Introduced	Fixed
Linux	Kernel	0	6.1.54
Linux	Kernel	3.8.0	6.1.54