CVE-2025-71065
Description
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to avoid potential deadlock
As Jiaming Zhang and syzbot reported, there is potential deadlock in f2fs as below:
Chain exists of: &sbi->cp_rwsem --> fs_reclaim --> sb_internal#2
Possible unsafe locking scenario:
CPU0 CPU1 ---- ---- rlock(sb_internal#2); lock(fs_reclaim); lock(sb_internal#2); rlock(&sbi->cp_rwsem);
* DEADLOCK *
3 locks held by kswapd0/73: #0: ffffffff8e247a40 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:7015 [inline] #0: ffffffff8e247a40 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x951/0x2800 mm/vmscan.c:7389 #1: ffff8880118400e0 (&type->s_umount_key#50){.+.+}-{4:4}, at: super_trylock_shared fs/super.c:562 [inline] #1: ffff8880118400e0 (&type->s_umount_key#50){.+.+}-{4:4}, at: super_cache_scan+0x91/0x4b0 fs/super.c:197 #2: ffff888011840610 (sb_internal#2){.+.+}-{0:0}, at: f2fs_evict_inode+0x8d9/0x1b60 fs/f2fs/inode.c:890
stack backtrace: CPU: 0 UID: 0 PID: 73 Comm: kswapd0 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace:
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043 check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 down_read+0x46/0x2e0 kernel/locking/rwsem.c:1537 f2fs_down_read fs/f2fs/f2fs.h:2278 [inline] f2fs_lock_op fs/f2fs/f2fs.h:2357 [inline] f2fs_do_truncate_blocks+0x21c/0x10c0 fs/f2fs/file.c:791 f2fs_truncate_blocks+0x10a/0x300 fs/f2fs/file.c:867 f2fs_truncate+0x489/0x7c0 fs/f2fs/file.c:925 f2fs_evict_inode+0x9f2/0x1b60 fs/f2fs/inode.c:897 evict+0x504/0x9c0 fs/inode.c:810 f2fs_evict_inode+0x1dc/0x1b60 fs/f2fs/inode.c:853 evict+0x504/0x9c0 fs/inode.c:810 dispose_list fs/inode.c:852 [inline] prune_icache_sb+0x21b/0x2c0 fs/inode.c:1000 super_cache_scan+0x39b/0x4b0 fs/super.c:224 do_shrink_slab+0x6ef/0x1110 mm/shrinker.c:437 shrink_slab_memcg mm/shrinker.c:550 [inline] shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628 shrink_one+0x28a/0x7c0 mm/vmscan.c:4955 shrink_many mm/vmscan.c:5016 [inline] lru_gen_shrink_node mm/vmscan.c:5094 [inline] shrink_node+0x315d/0x3780 mm/vmscan.c:6081 kswapd_shrink_node mm/vmscan.c:6941 [inline] balance_pgdat mm/vmscan.c:7124 [inline] kswapd+0x147c/0x2800 mm/vmscan.c:7389 kthread+0x70e/0x8a0 kernel/kthread.c:463 ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
The root cause is deadlock among four locks as below:
kswapd - fs_reclaim --- Lock A - shrink_one - evict - f2fs_evict_inode - sb_start_intwrite --- Lock B
- iput
- evict
- f2fs_evict_inode
- sb_start_intwrite --- Lock B
- f2fs_truncate
- f2fs_truncate_blocks
- f2fs_do_truncate_blocks
- f2fs_lock_op --- Lock C
ioctl - f2fs_ioc_commit_atomic_write - f2fs_lock_op --- Lock C - __f2fs_commit_atomic_write - __replace_atomic_write_block - f2fs_get_dnode_of_data - __get_node_folio - f2fs_check_nid_range - f2fs_handle_error - f2fs_record_errors - f2fs_down_write --- Lock D
open - do_open - do_truncate - security_inode_need_killpriv - f2fs_getxattr - lookup_all_xattrs - f2fs_handle_error - f2fs_record_errors - f2fs_down_write --- Lock D - f2fs_commit_super - read_mapping_folio - filemap_alloc_folio_noprof - prepare_alloc_pages - fs_reclaim_acquire --- Lock A
In order to a ---truncated---
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
A deadlock in the Linux kernel's f2fs filesystem can occur when memory reclaim triggers an inode eviction that tries to acquire a lock already held by the reclaim path.
Vulnerability
CVE-2025-71065 is a potential deadlock in the Linux kernel's f2fs (Flash-Friendly File System) implementation. The issue arises from a circular locking dependency between the filesystem's cp_rwsem (checkpoint read-write semaphore) and the memory reclaim subsystem (fs_reclaim path's sb_internal lock. When the kernel's page reclaim (kswapd) runs, it may hold fs_reclaim and sb_internal locks while trying to evict an inode. The inode eviction in f2fs then attempts to acquire cp_rwsem via f2fs_lock_op, creating a deadlock scenario if another thread already holds cp_rwsem and is waiting for memory allocation that requires sb_internal locks.
Exploitation
An attacker would need to trigger memory pressure (e.g., by exhausting available memory) to cause kswapd to run, and simultaneously have a filesystem operation that holds cp_rwsem and waits for memory. The deadlock can be triggered without special privileges if the attacker can cause sufficient memory pressure on a system using f2fs. The syzbot fuzzer and Jiaming Zhang reported this issue, indicating it can be reproduced under controlled conditions.
Impact
If the deadlock occurs, the system may become unresponsive as the kernel threads involved (kswapd and the filesystem operation) wait indefinitely for each other's locks. This can lead to a denial of service (DoS) condition, potentially affecting all processes that rely on filesystem or memory operations.
Mitigation
The fix has been applied to the Linux kernel stable tree. The commit referenced in the commit [1] and [2]. Users should update their kernel to a version containing the patch. No workaround is mentioned; the vulnerability is addressed by the kernel update.
AI Insight generated on May 19, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Affected products
2Patches
0No patches discovered yet.
Vulnerability mechanics
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References
4News mentions
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