syzbot
general protection fault in lmWriteRecord
Status:
moderation: reported on 2026/08/30 09:53
Subsystems:
jfs
Labels:
prio:low
[Documentation on labels]
Reported-by: syzbot+ba173472aba166849601@syzkaller.appspotmail.com
First crash: 4d05h, last: 4d05h
Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]
CPU: 1 UID: 0 PID: 7107 Comm: syz.1.253 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:lmWriteRecord+0x71/0x1ad0 fs/jfs/jfs_logmgr.c:366
Code: 44 24 50 42 80 3c 38 00 74 08 48 89 df e8 57 d5 cb fe 48 89 5c 24 30 48 8b 03 48 89 44 24 40 48 8d 58 38 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 30 d5 cb fe 4c 89 b4 24 98 00 00
RSP: 0018:ffffc9000b8d7600 EFLAGS: 00010202
RAX: 0000000000000007 RBX: 0000000000000038 RCX: 0000000000080000
RDX: ffffc90012f47000 RSI: 000000000000039f RDI: 00000000000003a0
RBP: 0000000000000100 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f63b50 R12: ffffc9000b8d7888
R13: ffffc90003831640 R14: ffffc9000b8d7888 R15: dffffc0000000000
FS: 00007fed6dfa46c0(0000) GS:ffff888125cde000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32123ffc CR3: 00000000331ae000 CR4: 00000000003526f0
Call Trace:
<TASK>
lmLog+0x6dc/0xa10 fs/jfs/jfs_logmgr.c:312
dtLog fs/jfs/jfs_txnmgr.c:1620 [inline]
txLog fs/jfs/jfs_txnmgr.c:1402 [inline]
txCommit+0x1c92/0x54a0 fs/jfs/jfs_txnmgr.c:1266
add_missing_indices+0x7e5/0xb30 fs/jfs/jfs_dtree.c:2671
jfs_readdir+0x1d15/0x33f0 fs/jfs/jfs_dtree.c:3028
wrap_directory_iterator+0x99/0xe0 fs/readdir.c:67
iterate_dir+0x2f1/0x4e0 fs/readdir.c:110
__do_sys_getdents fs/readdir.c:319 [inline]
__se_sys_getdents+0xf1/0x270 fs/readdir.c:304
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fed6fd8e0d9
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:00007fed6dfa4028 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00007fed70016180 RCX: 00007fed6fd8e0d9
RDX: 00000000000000b8 RSI: 0000200000000100 RDI: 0000000000000006
RBP: 00007fed6fe25024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fed70016218 R14: 00007fed70016180 R15: 00007ffe5c81f618
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:lmWriteRecord+0x71/0x1ad0 fs/jfs/jfs_logmgr.c:366
Code: 44 24 50 42 80 3c 38 00 74 08 48 89 df e8 57 d5 cb fe 48 89 5c 24 30 48 8b 03 48 89 44 24 40 48 8d 58 38 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 30 d5 cb fe 4c 89 b4 24 98 00 00
RSP: 0018:ffffc9000b8d7600 EFLAGS: 00010202
RAX: 0000000000000007 RBX: 0000000000000038 RCX: 0000000000080000
RDX: ffffc90012f47000 RSI: 000000000000039f RDI: 00000000000003a0
RBP: 0000000000000100 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f63b50 R12: ffffc9000b8d7888
R13: ffffc90003831640 R14: ffffc9000b8d7888 R15: dffffc0000000000
FS: 00007fed6dfa46c0(0000) GS:ffff888125cde000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32123ffc CR3: 00000000331ae000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 44 24 50 rex.R and $0x50,%al
3: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1)
8: 74 08 je 0x12
a: 48 89 df mov %rbx,%rdi
d: e8 57 d5 cb fe call 0xfecbd569
12: 48 89 5c 24 30 mov %rbx,0x30(%rsp)
17: 48 8b 03 mov (%rbx),%rax
1a: 48 89 44 24 40 mov %rax,0x40(%rsp)
1f: 48 8d 58 38 lea 0x38(%rax),%rbx
23: 48 89 d8 mov %rbx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 38 00 cmpb $0x0,(%rax,%r15,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 48 89 df mov %rbx,%rdi
34: e8 30 d5 cb fe call 0xfecbd569
39: 4c rex.WR
3a: 89 .byte 0x89
3b: b4 24 mov $0x24,%ah
3d: 98 cwtl
* Struck through repros no longer work on HEAD.