syzbot


general protection fault in mnt_want_write (3)

Status: upstream: reported C repro on 2026/02/07 22:03
Reported-by: syzbot+13dff099f2731732743b@syzkaller.appspotmail.com
First crash: 1d13h, last: 1d13h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-10 general protection fault in mnt_want_write (2) 2 1 725d 725d 0/2 auto-obsoleted due to no activity on 2024/05/15 10:15
android-6-1 general protection fault in mnt_want_write (2) origin:downstream 2 C 3 4d15h 19d 0/2 upstream: reported C repro on 2026/01/21 01:37
android-6-1 general protection fault in mnt_want_write 2 1 669d 669d 0/2 auto-obsoleted due to no activity on 2024/07/09 13:10
android-5-10 general protection fault in mnt_want_write 2 1 1418d 1418d 0/2 auto-closed as invalid on 2022/06/22 11:51

Sample crash report:
incfs: Can't find or create .incomplete dir in ./file0
incfs: mount failed -22
incfs: ino conflict with backing FS 2
general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 1 PID: 359 Comm: syz.2.18 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:mnt_want_write+0x2f/0x270 fs/namespace.c:363
Code: 57 41 56 41 55 41 54 53 50 48 89 fb 49 bd 00 00 00 00 00 fc ff df e8 b0 43 b6 ff 48 89 5d d0 48 83 c3 08 49 89 de 49 c1 ee 03 <43> 80 3c 2e 00 74 08 48 89 df e8 32 c1 f0 ff 4c 8b 3b 4d 8d a7 a8
RSP: 0018:ffffc90000c77ad0 EFLAGS: 00010202
RAX: ffffffff81ae7220 RBX: 0000000000000008 RCX: ffff8881101c93c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000c77b00 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200018ee34 R12: ffff88810d374770
R13: dffffc0000000000 R14: 0000000000000001 R15: dffffc0000000000
FS:  000055555562c500(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 000000010fd6d000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 ovl_want_write+0x92/0xa0 fs/overlayfs/util.c:21
 ovl_setattr+0x4a/0x720 fs/overlayfs/inode.c:28
 notify_change+0xab3/0xe40 fs/attr.c:410
 incfs_setattr+0x246/0x3c0 fs/incfs/vfs.c:1664
 notify_change+0xab3/0xe40 fs/attr.c:410
 chmod_common+0x1e1/0x390 fs/open.c:584
 do_fchmodat+0xd4/0x1a0 fs/open.c:622
 __do_sys_chmod fs/open.c:640 [inline]
 __se_sys_chmod fs/open.c:638 [inline]
 __x64_sys_chmod+0x60/0x70 fs/open.c:638
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7ffa3751feb9
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:00007ffd20e6d988 EFLAGS: 00000246 ORIG_RAX: 000000000000005a
RAX: ffffffffffffffda RBX: 00007ffa3779afa0 RCX: 00007ffa3751feb9
RDX: 0000000000000000 RSI: 0000000000000054 RDI: 0000200000000000
RBP: 00007ffa3758dc1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffa3779afac R14: 00007ffa3779afa0 R15: 00007ffa3779afa0
Modules linked in:
---[ end trace 7d35ea90ef849765 ]---
RIP: 0010:mnt_want_write+0x2f/0x270 fs/namespace.c:363
Code: 57 41 56 41 55 41 54 53 50 48 89 fb 49 bd 00 00 00 00 00 fc ff df e8 b0 43 b6 ff 48 89 5d d0 48 83 c3 08 49 89 de 49 c1 ee 03 <43> 80 3c 2e 00 74 08 48 89 df e8 32 c1 f0 ff 4c 8b 3b 4d 8d a7 a8
RSP: 0018:ffffc90000c77ad0 EFLAGS: 00010202
RAX: ffffffff81ae7220 RBX: 0000000000000008 RCX: ffff8881101c93c0
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90000c77b00 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff5200018ee34 R12: ffff88810d374770
R13: dffffc0000000000 R14: 0000000000000001 R15: dffffc0000000000
FS:  000055555562c500(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c005734000 CR3: 000000010fd6d000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	57                   	push   %rdi
   1:	41 56                	push   %r14
   3:	41 55                	push   %r13
   5:	41 54                	push   %r12
   7:	53                   	push   %rbx
   8:	50                   	push   %rax
   9:	48 89 fb             	mov    %rdi,%rbx
   c:	49 bd 00 00 00 00 00 	movabs $0xdffffc0000000000,%r13
  13:	fc ff df
  16:	e8 b0 43 b6 ff       	call   0xffb643cb
  1b:	48 89 5d d0          	mov    %rbx,-0x30(%rbp)
  1f:	48 83 c3 08          	add    $0x8,%rbx
  23:	49 89 de             	mov    %rbx,%r14
  26:	49 c1 ee 03          	shr    $0x3,%r14
* 2a:	43 80 3c 2e 00       	cmpb   $0x0,(%r14,%r13,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	48 89 df             	mov    %rbx,%rdi
  34:	e8 32 c1 f0 ff       	call   0xfff0c16b
  39:	4c 8b 3b             	mov    (%rbx),%r15
  3c:	4d                   	rex.WRB
  3d:	8d                   	.byte 0x8d
  3e:	a7                   	cmpsl  %es:(%rdi),%ds:(%rsi)
  3f:	a8                   	.byte 0xa8

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/07 22:02 android13-5.10-lts 58c592510fcd 4c131dc4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in mnt_want_write
* Struck through repros no longer work on HEAD.