syzbot
general protection fault in dbDiscardAG (2)
Status:
moderation: reported on 2026/09/30 01:35
Subsystems:
jfs
Labels:
prio:normal
[Documentation on labels]
Reported-by: syzbot+0266f74df36ca702aedf@syzkaller.appspotmail.com
First crash: 4d07h, last: 4d07h
Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
CPU: 1 UID: 0 PID: 8655 Comm: syz.2.356 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:dbDiscardAG+0x648/0x8f0 fs/jfs/jfs_dmap.c:1726
Code: 38 ad 8b e8 fa 4c c4 fd 4c 89 f7 e8 82 df 3c fe 4c 8b 74 24 10 49 83 c6 08 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 6a fe cd fe 49 c7 06 00 00 00 00 48
RSP: 0018:ffffc900058afcb0 EFLAGS: 00010206
RAX: 0000000000000003 RBX: ffff888028600000 RCX: dffffc0000000000
RDX: 0000000000000001 RSI: ffffffff8d86ca3b RDI: 00000000ffffffff
RBP: 0000000000000001 R08: ffffffff8fb2297f R09: 1ffffffff1f6452f
R10: dffffc0000000000 R11: fffffbfff1f64530 R12: ffffffffffffffff
R13: 0000000000000001 R14: 0000000000000018 R15: ffff888061a027a8
FS: 00007efc7fbf46c0(0000) GS:ffff888125cc4000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007efc77787000 CR3: 000000005953a000 CR4: 00000000003526f0
Call Trace:
<TASK>
jfs_ioc_trim+0x436/0x680 fs/jfs/jfs_discard.c:106
jfs_ioctl+0x291/0x3b0 fs/jfs/ioctl.c:131
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xff/0x170 fs/ioctl.c:583
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: 0033:0x7efc819de159
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:00007efc7fbf4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007efc81c66180 RCX: 00007efc819de159
RDX: 0000200000000080 RSI: 00000000c0185879 RDI: 0000000000000005
RBP: 00007efc81a7506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007efc81c66218 R14: 00007efc81c66180 R15: 00007ffd9a5fa7b8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dbDiscardAG+0x648/0x8f0 fs/jfs/jfs_dmap.c:1726
Code: 38 ad 8b e8 fa 4c c4 fd 4c 89 f7 e8 82 df 3c fe 4c 8b 74 24 10 49 83 c6 08 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 6a fe cd fe 49 c7 06 00 00 00 00 48
RSP: 0018:ffffc900058afcb0 EFLAGS: 00010206
RAX: 0000000000000003 RBX: ffff888028600000 RCX: dffffc0000000000
RDX: 0000000000000001 RSI: ffffffff8d86ca3b RDI: 00000000ffffffff
RBP: 0000000000000001 R08: ffffffff8fb2297f R09: 1ffffffff1f6452f
R10: dffffc0000000000 R11: fffffbfff1f64530 R12: ffffffffffffffff
R13: 0000000000000001 R14: 0000000000000018 R15: ffff888061a027a8
FS: 00007efc7fbf46c0(0000) GS:ffff888125cc4000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007efc77788000 CR3: 000000005953a000 CR4: 00000000003526f0
----------------
Code disassembly (best guess), 3 bytes skipped:
0: e8 fa 4c c4 fd call 0xfdc44cff
5: 4c 89 f7 mov %r14,%rdi
8: e8 82 df 3c fe call 0xfe3cdf8f
d: 4c 8b 74 24 10 mov 0x10(%rsp),%r14
12: 49 83 c6 08 add $0x8,%r14
16: 4c 89 f0 mov %r14,%rax
19: 48 c1 e8 03 shr $0x3,%rax
1d: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
24: fc ff df
* 27: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction
2b: 74 08 je 0x35
2d: 4c 89 f7 mov %r14,%rdi
30: e8 6a fe cd fe call 0xfecdfe9f
35: 49 c7 06 00 00 00 00 movq $0x0,(%r14)
3c: 48 rex.W
* Struck through repros no longer work on HEAD.