CVE-2024-56744 (published 2024-12-29)
In the Linux kernel, the following vulnerability has been resolved:

f2fs: fix to avoid potential deadlock in f2fs_record_stop_reason()

syzbot reports deadlock issue of f2fs as below:

======================================================
WARNING: possible circular locking dependency detected
6.12.0-rc3-syzkaller-00087-gc964ced77262 #0 Not tainted
------------------------------------------------------
kswapd0/79 is trying to acquire lock:
ffff888011824088 (&sbi->sb_lock){++++}-{3:3}, at: f2fs_down_write fs/f2fs/f2fs.h:2199 [inline]
ffff888011824088 (&sbi->sb_lock){++++}-{3:3}, at: f2fs_record_stop_reason+0x52/0x1d0 fs/f2fs/super.c:4068

but task is already holding lock:
ffff88804bd92610 (sb_internal#2){.+.+}-{0:0}, at: f2fs_evict_inode+0x662/0x15c0 fs/f2fs/inode.c:842

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (sb_internal#2){.+.+}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1716 [inline]
       sb_start_intwrite+0x4d/0x1c0 include/linux/fs.h:1899
       f2fs_evict_inode+0x662/0x15c0 fs/f2fs/inode.c:842
       evict+0x4e8/0x9b0 fs/inode.c:725
       f2fs_evict_inode+0x1a4/0x15c0 fs/f2fs/inode.c:807
       evict+0x4e8/0x9b0 fs/inode.c:725
       dispose_list fs/inode.c:774 [inline]
       prune_icache_sb+0x239/0x2f0 fs/inode.c:963
       super_cache_scan+0x38c/0x4b0 fs/super.c:223
       do_shrink_slab+0x701/0x1160 mm/shrinker.c:435
       shrink_slab+0x1093/0x14d0 mm/shrinker.c:662
       shrink_one+0x43b/0x850 mm/vmscan.c:4818
       shrink_many mm/vmscan.c:4879 [inline]
       lru_gen_shrink_node mm/vmscan.c:4957 [inline]
       shrink_node+0x3799/0x3de0 mm/vmscan.c:5937
       kswapd_shrink_node mm/vmscan.c:6765 [inline]
       balance_pgdat mm/vmscan.c:6957 [inline]
       kswapd+0x1ca3/0x3700 mm/vmscan.c:7226
       kthread+0x2f0/0x390 kernel/kthread.c:389
       ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
       ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #1 (fs_reclaim){+.+.}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5825
       __fs_reclaim_acquire mm/page_alloc.c:3834 [inline]
       fs_reclaim_acquire+0x88/0x130 mm/page_alloc.c:3848
       might_alloc include/linux/sched/mm.h:318 [inline]
       prepare_alloc_pages+0x147/0x5b0 mm/page_alloc.c:4493
       __alloc_pages_noprof+0x16f/0x710 mm/page_alloc.c:4722
       alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
       alloc_pages_noprof mm/mempolicy.c:2345 [inline]
       folio_alloc_noprof+0x128/0x180 mm/mempolicy.c:2352
       filemap_alloc_folio_noprof+0xdf/0x500 mm/filemap.c:1010
       do_read_cache_folio+0x2eb/0x850 mm/filemap.c:3787
       read_mapping_folio include/linux/pagemap.h:1011 [inline]
       f2fs_commit_super+0x3c0/0x7d0 fs/f2fs/super.c:4032
       f2fs_record_stop_reason+0x13b/0x1d0 fs/f2fs/super.c:4079
       f2fs_handle_critical_error+0x2ac/0x5c0 fs/f2fs/super.c:4174
       f2fs_write_inode+0x35f/0x4d0 fs/f2fs/inode.c:785
       write_inode fs/fs-writeback.c:1503 [inline]
       __writeback_single_inode+0x711/0x10d0 fs/fs-writeback.c:1723
       writeback_single_inode+0x1f3/0x660 fs/fs-writeback.c:1779
       sync_inode_metadata+0xc4/0x120 fs/fs-writeback.c:2849
       f2fs_release_file+0xa8/0x100 fs/f2fs/file.c:1941
       __fput+0x23f/0x880 fs/file_table.c:431
       task_work_run+0x24f/0x310 kernel/task_work.c:228
       resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
       exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
       exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
       __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
       syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218
       do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

---truncated---
Severity: MEDIUM (CVSS 3.1 vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H)
Weakness: CWE-667
Affected vendors: linux
Affected products: linux_kernel