WARNING in vfs_set_acl (4)

Status: moderation: reported on 2026/08/14 12:38
Subsystems: fs
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+f765fbdd39e66332718e@syzkaller.appspotmail.com
First crash: 4d07h, last: 4d07h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
3f097084 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in vfs_set_acl (4) 2026/08/12 02:44 2026/08/12 02:44 2026/08/12 03:26 f8d35649
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in vfs_set_acl fs -1 14 497d 662d 0/29 auto-obsoleted due to no activity on 2025/07/12 23:47
upstream WARNING in vfs_set_acl (2) fs -1 1 348d 344d 0/29 auto-obsoleted due to no activity on 2025/11/29 18:33
upstream WARNING in vfs_set_acl (3) fs prio:high -1 1 147d 143d 0/29 auto-obsoleted due to no activity on 2026/06/17 21:54

Sample crash report:
------------[ cut here ]------------
DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)): count = 0x0, magic = 0xffff88804cd1bb18, owner = 0x0, curr 0xffff8880333a3e00, list not empty
WARNING: kernel/locking/rwsem.c:1412 at __up_write kernel/locking/rwsem.c:1412 [inline], CPU#1: syz.7.1301/10983
WARNING: kernel/locking/rwsem.c:1412 at up_write+0x20f/0x5c0 kernel/locking/rwsem.c:1688, CPU#1: syz.7.1301/10983
Modules linked in:
CPU: 1 UID: 0 PID: 10983 Comm: syz.7.1301 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:__up_write kernel/locking/rwsem.c:1412 [inline]
RIP: 0010:up_write+0x226/0x5c0 kernel/locking/rwsem.c:1688
Code: 3c 02 00 0f 85 3e 03 00 00 48 8b 13 48 8d 3d f1 2a 40 0f 41 56 65 4c 8b 0d 9f 19 7e 12 4d 89 f8 4c 89 e1 48 c7 c6 40 e9 cf 8b <67> 48 0f b9 3a e8 30 f4 33 03 59 bf 01 00 00 00 e8 35 80 f0 ff 48
RSP: 0018:ffffc90006c37ab0 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88804cd1bb18 RCX: ffff88804cd1bb18
RDX: 0000000000000000 RSI: ffffffff8bcfe940 RDI: ffffffff91255160
RBP: ffff88804cd1bb20 R08: 0000000000000000 R09: ffff8880333a3e00
R10: ffff88804cd1bb1f R11: 0000000000000000 R12: ffff88804cd1bb18
R13: ffffffff9121f080 R14: ffffffff8bcfe760 R15: 0000000000000000
FS:  00007f4b1dae76c0(0000) GS:ffff888123eec000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe840755690 CR3: 00000000749d6000 CR4: 0000000000350ef0
Call Trace:
 <TASK>
 inode_unlock include/linux/fs.h:1034 [inline]
 vfs_set_acl+0x359/0x9e0 fs/posix_acl.c:1150
 do_set_acl+0xd9/0x1a0 fs/posix_acl.c:1286
 do_setxattr+0xeb/0x180 fs/xattr.c:659
 filename_setxattr+0x167/0x1d0 fs/xattr.c:690
 path_setxattrat+0x1ff/0x3b0 fs/xattr.c:734
 __do_sys_lsetxattr fs/xattr.c:775 [inline]
 __se_sys_lsetxattr fs/xattr.c:771 [inline]
 __x64_sys_lsetxattr+0xc9/0x140 fs/xattr.c:771
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4b1cb9e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f4b1dae7028 EFLAGS: 00000246 ORIG_RAX: 00000000000000bd
RAX: ffffffffffffffda RBX: 00007f4b1ce26090 RCX: 00007f4b1cb9e0d9
RDX: 0000200000000000 RSI: 0000200000000040 RDI: 0000200000000140
RBP: 00007f4b1cc35024 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000001c R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4b1ce26128 R14: 00007f4b1ce26090 R15: 00007ffc21800e38
 </TASK>
----------------
Code disassembly (best guess):
   0:	3c 02                	cmp    $0x2,%al
   2:	00 0f                	add    %cl,(%rdi)
   4:	85 3e                	test   %edi,(%rsi)
   6:	03 00                	add    (%rax),%eax
   8:	00 48 8b             	add    %cl,-0x75(%rax)
   b:	13 48 8d             	adc    -0x73(%rax),%ecx
   e:	3d f1 2a 40 0f       	cmp    $0xf402af1,%eax
  13:	41 56                	push   %r14
  15:	65 4c 8b 0d 9f 19 7e 	mov    %gs:0x127e199f(%rip),%r9        # 0x127e19bc
  1c:	12
  1d:	4d 89 f8             	mov    %r15,%r8
  20:	4c 89 e1             	mov    %r12,%rcx
  23:	48 c7 c6 40 e9 cf 8b 	mov    $0xffffffff8bcfe940,%rsi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e8 30 f4 33 03       	call   0x333f464
  34:	59                   	pop    %rcx
  35:	bf 01 00 00 00       	mov    $0x1,%edi
  3a:	e8 35 80 f0 ff       	call   0xfff08074
  3f:	48                   	rex.W

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/10 12:33 upstream db2ddb871435 558388e4 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root WARNING in vfs_set_acl
* Struck through repros no longer work on HEAD.