Bug 2420359 (CVE-2023-53829)

Summary: CVE-2023-53829 kernel: f2fs: flush inode if atomic file is aborted
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A kernel panic vulnerability was found in the F2FS filesystem in the Linux kernel. When an atomic file operation is aborted, the inode is not properly flushed, leaving it in a dirty state during eviction. This triggers f2fs_bug_on() in f2fs_evict_inode() when the FI_DIRTY_INODE flag is still set, causing a kernel panic. This can occur during filesystem unmount or process exit.
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Description OSIDB Bzimport 2025-12-09 02:05:29 UTC 
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---
Comment 1 Alexander B 2025-12-09 17:09:15 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025120953-CVE-2023-53829-2fe9@gregkh/T