syzbot
general protection fault in do_unlinkat
Status:
upstream: reported C repro on 2023/07/01 22:19
Bug presence:
origin:downstream
[Documentation on labels]
Reported-by: syzbot+7463da04bf95c393a7b7@syzkaller.appspotmail.com
First crash: 1122d, last: 6d11h
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Last patch testing requests (10)
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Fix bisection attempts (14)
Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]
CPU: 1 PID: 375 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:do_unlinkat+0x288/0x6c0 fs/namei.c:4389
Code: 44 89 ee e8 ca 4d ae ff 45 31 e4 41 81 fd 00 00 20 00 41 0f 95 c4 41 83 c4 eb e9 bd 00 00 00 49 8d 7e 30 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 4c 8b 7c 24 20 74 05 e8 27 d4 f3 ff 49 8b 46 30 48
RSP: 0018:ffffc900009a7e00 EFLAGS: 00010202
RAX: 0000000000000007 RBX: 1ffff11021fccf5a RCX: 0000000000000000
RDX: ffff888113a5d100 RSI: 0000000000000000 RDI: 0000000000000038
RBP: ffffc900009a7ee8 R08: ffffc900009a7ce7 R09: 1ffff92000134f9c
R10: dffffc0000000000 R11: fffff52000134f9d R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000008 R15: 0000000000000000
FS: 00007f2b5fbaf6c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2b5edeb580 CR3: 0000000115198000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__do_sys_unlink fs/namei.c:4445 [inline]
__se_sys_unlink fs/namei.c:4443 [inline]
__x64_sys_unlink+0x49/0x50 fs/namei.c:4443
x64_sys_call+0x958/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:88
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: 0033:0x7f2b5ed9de99
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:00007f2b5fbaf028 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 00007f2b5f025fa0 RCX: 00007f2b5ed9de99
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000080
RBP: 00007f2b5ee33eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f2b5f026038 R14: 00007f2b5f025fa0 R15: 00007ffc29af03d8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:do_unlinkat+0x288/0x6c0 fs/namei.c:4389
Code: 44 89 ee e8 ca 4d ae ff 45 31 e4 41 81 fd 00 00 20 00 41 0f 95 c4 41 83 c4 eb e9 bd 00 00 00 49 8d 7e 30 48 89 f8 48 c1 e8 03 <42> 80 3c 28 00 4c 8b 7c 24 20 74 05 e8 27 d4 f3 ff 49 8b 46 30 48
RSP: 0018:ffffc900009a7e00 EFLAGS: 00010202
RAX: 0000000000000007 RBX: 1ffff11021fccf5a RCX: 0000000000000000
RDX: ffff888113a5d100 RSI: 0000000000000000 RDI: 0000000000000038
RBP: ffffc900009a7ee8 R08: ffffc900009a7ce7 R09: 1ffff92000134f9c
R10: dffffc0000000000 R11: fffff52000134f9d R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000008 R15: 0000000000000000
FS: 00007f2b5fbaf6c0(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2b5edeb580 CR3: 0000000115198000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 44 89 ee mov %r13d,%esi
3: e8 ca 4d ae ff call 0xffae4dd2
8: 45 31 e4 xor %r12d,%r12d
b: 41 81 fd 00 00 20 00 cmp $0x200000,%r13d
12: 41 0f 95 c4 setne %r12b
16: 41 83 c4 eb add $0xffffffeb,%r12d
1a: e9 bd 00 00 00 jmp 0xdc
1f: 49 8d 7e 30 lea 0x30(%r14),%rdi
23: 48 89 f8 mov %rdi,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction
2f: 4c 8b 7c 24 20 mov 0x20(%rsp),%r15
34: 74 05 je 0x3b
36: e8 27 d4 f3 ff call 0xfff3d462
3b: 49 8b 46 30 mov 0x30(%r14),%rax
3f: 48 rex.W
* Struck through repros no longer work on HEAD.