syzbot


general protection fault in mntget

Status: premoderation: reported on 2026/04/26 03:42
Reported-by: syzbot+bbdfccb2daffd035d832@syzkaller.appspotmail.com
First crash: 4d00h, last: 4d00h
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 general protection fault in mntget 2 1 1d10h 1d10h 0/2 premoderation: reported on 2026/04/28 17:22
upstream KMSAN: uninit-value in enqueue_entity kernel 7 3 1533d 1575d 0/29 auto-closed as invalid on 2022/05/17 04:41

Sample crash report:
overlayfs: failed to create directory ./bus/work (errno: 22); mounting read-only
EXT4-fs (loop7): mounted filesystem without journal. Opts: ,errors=continue
ext4 filesystem being mounted at /5/bus/mnt supports timestamps until 2038-01-19 (0x7fffffff)
general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
CPU: 1 PID: 6327 Comm: syz.7.1538 Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:mnt_add_count fs/namespace.c:157 [inline]
RIP: 0010:mntget+0x2e/0x60 fs/namespace.c:1227
Code: 41 56 53 48 89 fb e8 41 05 b6 ff 48 85 db 74 30 e8 37 05 b6 ff 4c 8d 73 48 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 d4 86 f0 ff 49 8b 06 65 ff 00 eb 05
RSP: 0018:ffffc90000ecf640 EFLAGS: 00010206
RAX: 0000000000000009 RBX: 0000000000000001 RCX: dffffc0000000000
RDX: ffffc9000691d000 RSI: 0000000000000645 RDI: 0000000000000646
RBP: ffffc90000ecf650 R08: ffffc90000ecf6ef R09: 1ffff920001d9edd
R10: dffffc0000000000 R11: fffff520001d9ede R12: 0000000000000000
R13: ffff8881205bc801 R14: 0000000000000049 R15: ffffc90000ecf6e0
FS:  00007fa7826dc6c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c2fa653 CR3: 000000012135f000 CR4: 00000000003526a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 path_get+0x37/0x80 fs/namei.c:486
 get_incfs_backing_path fs/incfs/data_mgmt.h:541 [inline]
 file_open+0x1e5/0x650 fs/incfs/vfs.c:1473
 do_dentry_open+0x793/0x1090 fs/open.c:819
 open_with_fake_path+0x5a/0x90 fs/open.c:978
 ovl_open_realfile+0x161/0x1f0 fs/overlayfs/file.c:62
 ovl_open+0xdd/0x1f0 fs/overlayfs/file.c:158
 do_dentry_open+0x793/0x1090 fs/open.c:819
 vfs_open+0x73/0x80 fs/open.c:944
 do_open fs/namei.c:3399 [inline]
 path_openat+0x280f/0x31c0 fs/namei.c:3517
 do_filp_open+0x1e2/0x410 fs/namei.c:3544
 do_sys_openat2+0x19f/0x750 fs/open.c:1219
 do_sys_open fs/open.c:1235 [inline]
 __do_sys_openat fs/open.c:1251 [inline]
 __se_sys_openat fs/open.c:1246 [inline]
 __x64_sys_openat+0x136/0x160 fs/open.c:1246
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fa783c81dd9
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:00007fa7826dc028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fa783efafa0 RCX: 00007fa783c81dd9
RDX: 0000000000080800 RSI: 0000200000000140 RDI: ffffffffffffff9c
RBP: 00007fa783d17d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa783efb038 R14: 00007fa783efafa0 R15: 00007ffecf221358
Modules linked in:
---[ end trace 9546994447eb801a ]---
RIP: 0010:mnt_add_count fs/namespace.c:157 [inline]
RIP: 0010:mntget+0x2e/0x60 fs/namespace.c:1227
Code: 41 56 53 48 89 fb e8 41 05 b6 ff 48 85 db 74 30 e8 37 05 b6 ff 4c 8d 73 48 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 d4 86 f0 ff 49 8b 06 65 ff 00 eb 05
RSP: 0018:ffffc90000ecf640 EFLAGS: 00010206
RAX: 0000000000000009 RBX: 0000000000000001 RCX: dffffc0000000000
RDX: ffffc9000691d000 RSI: 0000000000000645 RDI: 0000000000000646
RBP: ffffc90000ecf650 R08: ffffc90000ecf6ef R09: 1ffff920001d9edd
R10: dffffc0000000000 R11: fffff520001d9ede R12: 0000000000000000
R13: ffff8881205bc801 R14: 0000000000000049 R15: ffffc90000ecf6e0
FS:  00007fa7826dc6c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f50b315b2f8 CR3: 000000012135f000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	41 56                	push   %r14
   2:	53                   	push   %rbx
   3:	48 89 fb             	mov    %rdi,%rbx
   6:	e8 41 05 b6 ff       	call   0xffb6054c
   b:	48 85 db             	test   %rbx,%rbx
   e:	74 30                	je     0x40
  10:	e8 37 05 b6 ff       	call   0xffb6054c
  15:	4c 8d 73 48          	lea    0x48(%rbx),%r14
  19:	4c 89 f0             	mov    %r14,%rax
  1c:	48 c1 e8 03          	shr    $0x3,%rax
  20:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  27:	fc ff df
* 2a:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	4c 89 f7             	mov    %r14,%rdi
  33:	e8 d4 86 f0 ff       	call   0xfff0870c
  38:	49 8b 06             	mov    (%r14),%rax
  3b:	65 ff 00             	incl   %gs:(%rax)
  3e:	eb 05                	jmp    0x45

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/26 03:41 android13-5.10-lts d8c55bf860fd 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in mntget
* Struck through repros no longer work on HEAD.