[moderation] [kernel?] general protection fault in detach_timer (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c22e26bd0906 Merge tag 'landlock-7.0-rc1' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11325c02580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6428d17febdfb14e
dashboard link: https://syzkaller.appspot.com/bug?extid=d3fab1eb138a95ff0337
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [linux-...@vger.kernel.org pet...@infradead.org tg...@kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b33c549157ca/disk-c22e26bd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/34c7ded19553/vmlinux-c22e26bd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/66faec2158ed/bzImage-c22e26bd.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d3fab1...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xfbd59c0000000025: 0000 [#1] SMP KASAN PTI
KASAN: maybe wild-memory-access in range [0xdead000000000128-0xdead00000000012f]
CPU: 0 UID: 0 PID: 16 Comm: ktimers/0 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:__hlist_del include/linux/list.h:994 [inline]
RIP: 0010:detach_timer+0x120/0x2b0 kernel/time/timer.c:891
Code: c1 e8 03 80 3c 28 00 74 08 4c 89 e7 e8 39 bb 78 00 4d 89 3c 24 4d 85 ff 74 46 e8 cb a0 13 00 49 83 c7 08 4c 89 f8 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 ff e8 12 bb 78 00 4d 89 27 80 7c 24 04 00
RSP: 0018:ffffc90000157af8 EFLAGS: 00010802
RAX: 1bd5a00000000025 RBX: 1ffff1100c29ebe7 RCX: ffff88801cad8000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000100
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000100
R10: dffffc0000000000 R11: fffffbfff1e9250f R12: ffffc90000157c08
R13: ffff8880614f5f40 R14: 1ffff1100c29ebe8 R15: dead00000000012a
FS: 0000000000000000(0000) GS:ffff888126595000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200001000000 CR3: 000000000d9ba000 CR4: 00000000003526f0
Call Trace:
<TASK>
expire_timers kernel/time/timer.c:1782 [inline]
__run_timers kernel/time/timer.c:2373 [inline]
__run_timer_base+0x624/0x9f0 kernel/time/timer.c:2385
run_timer_base kernel/time/timer.c:2394 [inline]
run_timer_softirq+0xb7/0x170 kernel/time/timer.c:2404
handle_softirqs+0x1de/0x640 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
run_ktimerd+0x69/0x100 kernel/softirq.c:1138
smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
kthread+0x388/0x470 kernel/kthread.c:467
ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:__hlist_del include/linux/list.h:994 [inline]
RIP: 0010:detach_timer+0x120/0x2b0 kernel/time/timer.c:891
Code: c1 e8 03 80 3c 28 00 74 08 4c 89 e7 e8 39 bb 78 00 4d 89 3c 24 4d 85 ff 74 46 e8 cb a0 13 00 49 83 c7 08 4c 89 f8 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 ff e8 12 bb 78 00 4d 89 27 80 7c 24 04 00
RSP: 0018:ffffc90000157af8 EFLAGS: 00010802
RAX: 1bd5a00000000025 RBX: 1ffff1100c29ebe7 RCX: ffff88801cad8000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000100
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000100
R10: dffffc0000000000 R11: fffffbfff1e9250f R12: ffffc90000157c08
R13: ffff8880614f5f40 R14: 1ffff1100c29ebe8 R15: dead00000000012a
FS: 0000000000000000(0000) GS:ffff888126595000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200001000000 CR3: 000000000d9ba000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: c1 e8 03 shr $0x3,%eax
3: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1)
7: 74 08 je 0x11
9: 4c 89 e7 mov %r12,%rdi
c: e8 39 bb 78 00 call 0x78bb4a
11: 4d 89 3c 24 mov %r15,(%r12)
15: 4d 85 ff test %r15,%r15
18: 74 46 je 0x60
1a: e8 cb a0 13 00 call 0x13a0ea
1f: 49 83 c7 08 add $0x8,%r15
23: 4c 89 f8 mov %r15,%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 ff mov %r15,%rdi
33: e8 12 bb 78 00 call 0x78bb4a
38: 4d 89 27 mov %r12,(%r15)
3b: 80 7c 24 04 00 cmpb $0x0,0x4(%rsp)


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