[syzbot] [edac?] general protection fault in detach_timer (3)

[syzbot <syzbot+edc6b57cbed1fb72d0f9@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    cc2b5f627e8c Add linux-next specific files for 20260714
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=17ba25b9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2290ccbf984c524f
dashboard link: https://syzkaller.appspot.com/bug?extid=edc6b57cbed1fb72d0f9
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13334aea580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=156ce249580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6836f8efb1da/disk-cc2b5f62.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0109d3477cc7/vmlinux-cc2b5f62.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c2e49e350bbf/bzImage-cc2b5f62.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+edc6b57cbed1fb72d0f9@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 07/24/2026
RIP: 0010:__hlist_del include/linux/list.h:1031 [inline]
RIP: 0010:detach_timer+0x120/0x2d0 kernel/time/timer.c:891
Code: c1 e8 03 80 3c 28 00 74 08 4c 89 e7 e8 a9 51 80 00 4d 89 3c 24 4d 85 ff 74 46 e8 cb f9 13 00 49 83 c7 08 4c 89 f8 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 ff e8 82 51 80 00 4d 89 27 80 7c 24 04 00
RSP: 0018:ffffc90000157af8 EFLAGS: 00010802
RAX: 1bd5a00000000025 RBX: 1ffff110170e4694 RCX: ffff88801daf8000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000100
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000100
R10: dffffc0000000000 R11: fffffbfff1fa1890 R12: ffffc90000157c00
R13: ffff8880b87234a8 R14: 1ffff110170e4695 R15: dead00000000012a
FS:  0000000000000000(0000) GS:ffff8881259f2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7a50cf012d CR3: 000000004485e000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 expire_timers kernel/time/timer.c:1782 [inline]
 __run_timers kernel/time/timer.c:2374 [inline]
 __run_timer_base+0x5f8/0x9b0 kernel/time/timer.c:2386
 run_timer_base kernel/time/timer.c:2395 [inline]
 run_timer_softirq+0x67/0x170 kernel/time/timer.c:2403
 handle_softirqs+0x1d9/0x6c0 kernel/softirq.c:626
 __do_softirq kernel/softirq.c:660 [inline]
 run_ktimerd+0x69/0x100 kernel/softirq.c:1155
 smpboot_thread_fn+0x57c/0xa80 kernel/smpboot.c:160
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 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:1031 [inline]
RIP: 0010:detach_timer+0x120/0x2d0 kernel/time/timer.c:891
Code: c1 e8 03 80 3c 28 00 74 08 4c 89 e7 e8 a9 51 80 00 4d 89 3c 24 4d 85 ff 74 46 e8 cb f9 13 00 49 83 c7 08 4c 89 f8 48 c1 e8 03 <80> 3c 28 00 74 08 4c 89 ff e8 82 51 80 00 4d 89 27 80 7c 24 04 00
RSP: 0018:ffffc90000157af8 EFLAGS: 00010802
RAX: 1bd5a00000000025 RBX: 1ffff110170e4694 RCX: ffff88801daf8000
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000100
RBP: dffffc0000000000 R08: 0000000000000000 R09: 0000000000000100
R10: dffffc0000000000 R11: fffffbfff1fa1890 R12: ffffc90000157c00
R13: ffff8880b87234a8 R14: 1ffff110170e4695 R15: dead00000000012a
FS:  0000000000000000(0000) GS:ffff8881259f2000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7a50cf012d CR3: 000000004485e000 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 a9 51 80 00       	call   0x8051ba
  11:	4d 89 3c 24          	mov    %r15,(%r12)
  15:	4d 85 ff             	test   %r15,%r15
  18:	74 46                	je     0x60
  1a:	e8 cb f9 13 00       	call   0x13f9ea
  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 82 51 80 00       	call   0x8051ba
  38:	4d 89 27             	mov    %r12,(%r15)
  3b:	80 7c 24 04 00       	cmpb   $0x0,0x4(%rsp)


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