syzbot
general protection fault in detach_timer (3)
Status:
upstream: reported C repro on 2026/07/31 17:15
Subsystems:
edac
Labels:
prio:high
[Documentation on labels]
Reported-by: syzbot+edc6b57cbed1fb72d0f9@syzkaller.appspotmail.com
First crash: 16d, last: 4d18h
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Last patch testing requests (1)
Sample crash report:
smpboot: CPU 1 is now offline
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 5673 Comm: syz-executor341 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:__hlist_del include/linux/list.h:1029 [inline]
RIP: 0010:detach_timer+0xf9/0x2d0 kernel/time/timer.c:891
Code: 24 08 49 83 c5 08 4d 89 ee 49 c1 ee 03 4c 89 e5 43 80 3c 26 00 74 08 4c 89 ef e8 f2 47 7d 00 4d 8b 65 00 4c 89 e0 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 e7 e8 c9 48 7d 00 4d 89 3c 24 4d 85 ff 74
RSP: 0018:ffffc900046378b0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 1ffff110170e4694 RCX: ffff88803856be00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f5e987 R12: 0000000000000000
R13: ffff8880b87234a8 R14: 1ffff110170e4695 R15: dead000000000122
FS: 00007f9df5c376c0(0000) GS:ffff888125c46000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe09c7a83c CR3: 000000001147e000 CR4: 00000000003526f0
Call Trace:
<TASK>
migrate_timer_list kernel/time/timer.c:2493 [inline]
timers_dead_cpu+0x32e/0x560 kernel/time/timer.c:2541
cpuhp_invoke_callback+0x434/0x810 kernel/cpu.c:194
__cpuhp_invoke_callback_range kernel/cpu.c:972 [inline]
cpuhp_invoke_callback_range kernel/cpu.c:996 [inline]
cpuhp_down_callbacks kernel/cpu.c:1386 [inline]
_cpu_down+0x343/0x840 kernel/cpu.c:1457
cpu_down_maps_locked kernel/cpu.c:1483 [inline]
cpu_down kernel/cpu.c:1491 [inline]
cpu_device_down+0x82/0xc0 kernel/cpu.c:1508
device_offline+0x2d2/0x3c0 drivers/base/core.c:4279
online_store+0x123/0x1a0 drivers/base/core.c:2879
kernfs_fop_write_iter+0x3a5/0x540 fs/kernfs/file.c:345
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x61e/0xbb0 fs/read_write.c:687
ksys_write+0x156/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9df5c5f909
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9df5c371d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f9df5d11b48 RCX: 00007f9df5c5f909
RDX: 0000000000000002 RSI: 0000200000000180 RDI: 0000000000000003
RBP: 00007f9df5d11b40 R08: 35203a6b63617473 R09: 35203a6b63617473
R10: 35203a6b63617473 R11: 0000000000000246 R12: 00007f9df5cde4d4
R13: 0000200000000700 R14: 0000200000000180 R15: 00002000000001a0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__hlist_del include/linux/list.h:1029 [inline]
RIP: 0010:detach_timer+0xf9/0x2d0 kernel/time/timer.c:891
Code: 24 08 49 83 c5 08 4d 89 ee 49 c1 ee 03 4c 89 e5 43 80 3c 26 00 74 08 4c 89 ef e8 f2 47 7d 00 4d 8b 65 00 4c 89 e0 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 e7 e8 c9 48 7d 00 4d 89 3c 24 4d 85 ff 74
RSP: 0018:ffffc900046378b0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 1ffff110170e4694 RCX: ffff88803856be00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f5e987 R12: 0000000000000000
R13: ffff8880b87234a8 R14: 1ffff110170e4695 R15: dead000000000122
FS: 00007f9df5c376c0(0000) GS:ffff888125c46000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe09c7a83c CR3: 000000001147e000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 24 08 and $0x8,%al
2: 49 83 c5 08 add $0x8,%r13
6: 4d 89 ee mov %r13,%r14
9: 49 c1 ee 03 shr $0x3,%r14
d: 4c 89 e5 mov %r12,%rbp
10: 43 80 3c 26 00 cmpb $0x0,(%r14,%r12,1)
15: 74 08 je 0x1f
17: 4c 89 ef mov %r13,%rdi
1a: e8 f2 47 7d 00 call 0x7d4811
1f: 4d 8b 65 00 mov 0x0(%r13),%r12
23: 4c 89 e0 mov %r12,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 4c 89 e7 mov %r12,%rdi
33: e8 c9 48 7d 00 call 0x7d4901
38: 4d 89 3c 24 mov %r15,(%r12)
3c: 4d 85 ff test %r15,%r15
3f: 74 .byte 0x74
* Struck through repros no longer work on HEAD.