syzbot
general protection fault in start_creating
Status:
upstream: reported C repro on 2026/08/19 20:46
Bug presence:
origin:lts-only
[Documentation on labels]
Reported-by: syzbot+489204306b2bf26cd786@syzkaller.appspotmail.com
First crash: 56d, last: 27d
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Bug presence (2)
| Date |
Name |
Commit |
Repro |
Result |
| 2026/09/18 |
linux-5.15.y (ToT) |
0248c33e835e |
C
|
[report] general protection fault in start_creating
|
| 2026/09/18 |
upstream (ToT) |
5dd1818b15d9 |
C
|
Didn't crash |
Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc000000002a: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000150-0x0000000000000157]
CPU: 0 PID: 4421 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__lock_acquire+0xf8/0x7b50 kernel/locking/lockdep.c:4882
Code: 42 0f b6 04 00 84 c0 0f 85 2d 64 00 00 83 3d 02 55 2e 0c 00 0f 84 ee 26 00 00 83 3d d1 f0 c1 0a 00 74 2a 4c 89 e8 48 c1 e8 03 <42> 80 3c 00 00 74 12 4c 89 ef e8 89 4c 61 00 49 b8 00 00 00 00 00
RSP: 0018:ffffc900035cf460 EFLAGS: 00010002
RAX: 000000000000002a RBX: 0000000000000000 RCX: 1ffff920006b9eac
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000150
RBP: ffffc900035cf690 R08: dffffc0000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1b16246 R12: 0000000000000001
R13: 0000000000000150 R14: 0000000000000000 R15: 0000000000000000
FS: 00007ff02afb56c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff02af93ff8 CR3: 0000000077bb5000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623
down_write+0x38/0x60 kernel/locking/rwsem.c:1551
inode_lock include/linux/fs.h:793 [inline]
start_creating+0x129/0x310 fs/debugfs/inode.c:350
__debugfs_create_file+0x6f/0x500 fs/debugfs/inode.c:399
debugfs_create_files block/blk-mq-debugfs.c:821 [inline]
blk_mq_debugfs_register_hctx+0x3f2/0x7b0 block/blk-mq-debugfs.c:888
blk_mq_debugfs_register+0x4a5/0x7e0 block/blk-mq-debugfs.c:843
blk_register_queue+0x204/0x3a0 block/blk-sysfs.c:878
device_add_disk+0x589/0xd00 block/genhd.c:490
null_add_dev+0xe81/0x1630 drivers/block/null_blk/main.c:1913
nullb_device_power_store+0x241/0x370 drivers/block/null_blk/main.c:390
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x30b/0x400 fs/configfs/file.c:229
call_write_iter include/linux/fs.h:2179 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0x748/0xd70 fs/read_write.c:594
ksys_write+0x153/0x260 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7ff02b976159
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:00007ff02afb5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007ff02bbfe090 RCX: 00007ff02b976159
RDX: 0000000000000001 RSI: 0000200000000200 RDI: 0000000000000007
RBP: 00007ff02ba0d03b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff02bbfe128 R14: 00007ff02bbfe090 R15: 00007ffd1312ef08
</TASK>
Modules linked in:
---[ end trace 3e242b74a7acf226 ]---
RIP: 0010:__lock_acquire+0xf8/0x7b50 kernel/locking/lockdep.c:4882
Code: 42 0f b6 04 00 84 c0 0f 85 2d 64 00 00 83 3d 02 55 2e 0c 00 0f 84 ee 26 00 00 83 3d d1 f0 c1 0a 00 74 2a 4c 89 e8 48 c1 e8 03 <42> 80 3c 00 00 74 12 4c 89 ef e8 89 4c 61 00 49 b8 00 00 00 00 00
RSP: 0018:ffffc900035cf460 EFLAGS: 00010002
RAX: 000000000000002a RBX: 0000000000000000 RCX: 1ffff920006b9eac
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000150
RBP: ffffc900035cf690 R08: dffffc0000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1b16246 R12: 0000000000000001
R13: 0000000000000150 R14: 0000000000000000 R15: 0000000000000000
FS: 00007ff02afb56c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff02af93ff8 CR3: 0000000077bb5000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 42 0f b6 04 00 movzbl (%rax,%r8,1),%eax
5: 84 c0 test %al,%al
7: 0f 85 2d 64 00 00 jne 0x643a
d: 83 3d 02 55 2e 0c 00 cmpl $0x0,0xc2e5502(%rip) # 0xc2e5516
14: 0f 84 ee 26 00 00 je 0x2708
1a: 83 3d d1 f0 c1 0a 00 cmpl $0x0,0xac1f0d1(%rip) # 0xac1f0f2
21: 74 2a je 0x4d
23: 4c 89 e8 mov %r13,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 00 00 cmpb $0x0,(%rax,%r8,1) <-- trapping instruction
2f: 74 12 je 0x43
31: 4c 89 ef mov %r13,%rdi
34: e8 89 4c 61 00 call 0x614cc2
39: 49 rex.WB
3a: b8 00 00 00 00 mov $0x0,%eax
* Struck through repros no longer work on HEAD.