syzbot


general protection fault in loop_process_work

Status: upstream: reported on 2025/11/11 23:23
Reported-by: syzbot+448b3e3c16e3acb2a031@syzkaller.appspotmail.com
First crash: 6d22h, last: 6d22h
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream general protection fault in loop_process_work (2) block 2 1 757d 753d 0/29 auto-obsoleted due to no activity on 2024/01/21 18:59
upstream general protection fault in loop_process_work block 2 1 864d 860d 0/29 auto-obsoleted due to no activity on 2023/10/06 02:37
upstream BUG: corrupted list in loop_process_work block 8 C done 1809 265d 277d 0/29 auto-obsoleted due to no activity on 2025/07/31 07:30

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0000000032: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000190-0x0000000000000197]
CPU: 1 PID: 1134 Comm: kworker/u4:5 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: loop0 loop_workfn
RIP: 0010:file_inode include/linux/fs.h:1075 [inline]
RIP: 0010:file_start_write include/linux/fs.h:2709 [inline]
RIP: 0010:lo_write_bvec drivers/block/loop.c:243 [inline]
RIP: 0010:lo_write_simple drivers/block/loop.c:266 [inline]
RIP: 0010:do_req_filebacked drivers/block/loop.c:490 [inline]
RIP: 0010:loop_handle_cmd drivers/block/loop.c:1933 [inline]
RIP: 0010:loop_process_work+0xee0/0x1ed0 drivers/block/loop.c:1968
Code: be 01 00 00 00 48 8d 94 24 00 02 00 00 e8 28 af db fe 4d 8d a7 90 01 00 00 4d 89 e5 49 c1 ed 03 48 b8 00 00 00 00 00 fc ff df <41> 80 7c 05 00 00 74 08 4c 89 e7 e8 70 3a 9b fc 49 8b 1c 24 48 89
RSP: 0018:ffffc9000455f940 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000001000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc9000455fae8
RBP: ffffc9000455fbb0 R08: 0000000000000004 R09: 0000000000000004
R10: ffffc9000455fad4 R11: fffff520008abf5c R12: 0000000000000190
R13: 0000000000000032 R14: ffffc9000455fad0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055556a896588 CR3: 000000001bb10000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:file_inode include/linux/fs.h:1075 [inline]
RIP: 0010:file_start_write include/linux/fs.h:2709 [inline]
RIP: 0010:lo_write_bvec drivers/block/loop.c:243 [inline]
RIP: 0010:lo_write_simple drivers/block/loop.c:266 [inline]
RIP: 0010:do_req_filebacked drivers/block/loop.c:490 [inline]
RIP: 0010:loop_handle_cmd drivers/block/loop.c:1933 [inline]
RIP: 0010:loop_process_work+0xee0/0x1ed0 drivers/block/loop.c:1968
Code: be 01 00 00 00 48 8d 94 24 00 02 00 00 e8 28 af db fe 4d 8d a7 90 01 00 00 4d 89 e5 49 c1 ed 03 48 b8 00 00 00 00 00 fc ff df <41> 80 7c 05 00 00 74 08 4c 89 e7 e8 70 3a 9b fc 49 8b 1c 24 48 89
RSP: 0018:ffffc9000455f940 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000001000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffc9000455fae8
RBP: ffffc9000455fbb0 R08: 0000000000000004 R09: 0000000000000004
R10: ffffc9000455fad4 R11: fffff520008abf5c R12: 0000000000000190
R13: 0000000000000032 R14: ffffc9000455fad0 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f07f4ef0000 CR3: 0000000023df6000 CR4: 00000000003506f0
----------------
Code disassembly (best guess):
   0:	be 01 00 00 00       	mov    $0x1,%esi
   5:	48 8d 94 24 00 02 00 	lea    0x200(%rsp),%rdx
   c:	00
   d:	e8 28 af db fe       	call   0xfedbaf3a
  12:	4d 8d a7 90 01 00 00 	lea    0x190(%r15),%r12
  19:	4d 89 e5             	mov    %r12,%r13
  1c:	49 c1 ed 03          	shr    $0x3,%r13
  20:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  27:	fc ff df
* 2a:	41 80 7c 05 00 00    	cmpb   $0x0,0x0(%r13,%rax,1) <-- trapping instruction
  30:	74 08                	je     0x3a
  32:	4c 89 e7             	mov    %r12,%rdi
  35:	e8 70 3a 9b fc       	call   0xfc9b3aaa
  3a:	49 8b 1c 24          	mov    (%r12),%rbx
  3e:	48                   	rex.W
  3f:	89                   	.byte 0x89

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/11 23:22 linux-6.6.y 0a805b6ea8cd 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan general protection fault in loop_process_work
* Struck through repros no longer work on HEAD.