syzbot
general protection fault in mntget
Status:
premoderation: reported on 2026/06/29 06:22
Reported-by: syzbot+8f7cd4423c046999f82a@syzkaller.appspotmail.com
First crash: 42d, last: 9h02m
Sample crash report:
overlayfs: failed to create directory ./bus/work (errno: 22); mounting read-only
general protection fault, probably for non-canonical address 0xdffffc000000000a: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000050-0x0000000000000057]
CPU: 0 PID: 522 Comm: syz.4.56 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:mnt_add_count fs/namespace.c:179 [inline]
RIP: 0010:mntget+0x2e/0x60 fs/namespace.c:1296
Code: 41 56 53 48 89 fb e8 41 95 a9 ff 48 85 db 74 30 e8 37 95 a9 ff 4c 8d 73 50 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 c4 1f ef ff 49 8b 06 65 ff 00 eb 05
RSP: 0018:ffffc9000f7275c0 EFLAGS: 00010206
RAX: 000000000000000a RBX: 0000000000000001 RCX: dffffc0000000000
RDX: ffffc90003b13000 RSI: 000000000000258f RDI: 0000000000002590
RBP: ffffc9000f7275d0 R08: ffffc9000f72766f R09: 1ffff92001ee4ecd
R10: dffffc0000000000 R11: fffff52001ee4ece R12: 0000000000000000
R13: ffffc9000f727601 R14: 0000000000000051 R15: ffffc9000f727660
FS: 00007fa9b0a2c6c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000013a976000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
path_get+0x37/0x80 fs/namei.c:547
get_incfs_backing_path fs/incfs/data_mgmt.h:541 [inline]
file_open+0x1e3/0x680 fs/incfs/vfs.c:1496
do_dentry_open+0x885/0x11f0 fs/open.c:884
open_with_fake_path+0x5a/0x90 fs/open.c:1093
ovl_open_realfile+0x20c/0x290 fs/overlayfs/file.c:66
ovl_open+0x168/0x2e0 fs/overlayfs/file.c:163
do_dentry_open+0x885/0x11f0 fs/open.c:884
vfs_open+0x73/0x80 fs/open.c:1017
do_open fs/namei.c:3633 [inline]
path_openat+0x2699/0x2f30 fs/namei.c:3790
do_filp_open+0x1ee/0x420 fs/namei.c:3817
do_sys_openat2+0x15e/0x820 fs/open.c:1343
do_sys_open fs/open.c:1359 [inline]
__do_sys_openat fs/open.c:1375 [inline]
__se_sys_openat fs/open.c:1370 [inline]
__x64_sys_openat+0x136/0x160 fs/open.c:1370
x64_sys_call+0x783/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa9afb9e0d9
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:00007fa9b0a2c028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fa9afe25fa0 RCX: 00007fa9afb9e0d9
RDX: 0000000000020040 RSI: 0000200000000340 RDI: ffffffffffffff9c
RBP: 00007fa9afc35024 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000000001ff R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa9afe26038 R14: 00007fa9afe25fa0 R15: 00007ffc1cef04f8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:mnt_add_count fs/namespace.c:179 [inline]
RIP: 0010:mntget+0x2e/0x60 fs/namespace.c:1296
Code: 41 56 53 48 89 fb e8 41 95 a9 ff 48 85 db 74 30 e8 37 95 a9 ff 4c 8d 73 50 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 c4 1f ef ff 49 8b 06 65 ff 00 eb 05
RSP: 0018:ffffc9000f7275c0 EFLAGS: 00010206
RAX: 000000000000000a RBX: 0000000000000001 RCX: dffffc0000000000
RDX: ffffc90003b13000 RSI: 000000000000258f RDI: 0000000000002590
RBP: ffffc9000f7275d0 R08: ffffc9000f72766f R09: 1ffff92001ee4ecd
R10: dffffc0000000000 R11: fffff52001ee4ece R12: 0000000000000000
R13: ffffc9000f727601 R14: 0000000000000051 R15: ffffc9000f727660
FS: 00007fa9b0a2c6c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa9afbeb7c0 CR3: 000000013a976000 CR4: 00000000003506a0
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 95 a9 ff call 0xffa9954c
b: 48 85 db test %rbx,%rbx
e: 74 30 je 0x40
10: e8 37 95 a9 ff call 0xffa9954c
15: 4c 8d 73 50 lea 0x50(%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 c4 1f ef ff call 0xffef1ffc
38: 49 8b 06 mov (%r14),%rax
3b: 65 ff 00 incl %gs:(%rax)
3e: eb 05 jmp 0x45
* Struck through repros no longer work on HEAD.