syzbot


general protection fault in loopback_jiffies_timer_pos_update (2)

Status: moderation: reported on 2025/07/31 12:40
Subsystems: sound
[Documentation on labels]
Reported-by: syzbot+c8055d5b9745e94e205f@syzkaller.appspotmail.com
First crash: 50d, last: 50d
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream general protection fault in loopback_jiffies_timer_pos_update sound 2 1 769d 765d 0/29 auto-obsoleted due to no activity on 2023/11/06 13:26
linux-6.6 general protection fault in loopback_jiffies_timer_pos_update origin:upstream 2 syz 3 21d 24d 0/2 upstream: reported syz repro on 2025/08/22 01:56
upstream BUG: unable to handle kernel NULL pointer dereference in loopback_jiffies_timer_pos_update sound 10 1 1092d 1088d 0/29 auto-obsoleted due to no activity on 2022/12/18 13:48

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
CPU: 3 UID: 0 PID: 0 Comm: swapper/3 Not tainted 6.16.0-rc7-syzkaller-00140-gec2df4364666 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:loopback_jiffies_timer_pos_update+0xc5a/0xfe0 sound/drivers/aloop.c:663
Code: 18 5b 5d 41 5c 41 5d 41 5e 41 5f e9 d0 22 5f 02 e8 fb 87 91 f8 48 8d 7d 48 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 3e 03 00 00 4d 89 fc 4c 2b 65 48 4c 89 7d 48 31
RSP: 0018:ffffc900006f8be0 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: ffff888025bf8600 RCX: ffffffff892a58ad
RDX: 0000000000000009 RSI: ffffffff892a6095 RDI: 0000000000000048
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000001 R12: 0000000000000002
R13: 0000000000000002 R14: 0000000000000003 R15: 00000000ffffc246
FS:  0000000000000000(0000) GS:ffff8880d6a20000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000031788000 CR4: 0000000000352ef0
Call Trace:
 <IRQ>
 loopback_jiffies_timer_function+0xdb/0x240 sound/drivers/aloop.c:706
 call_timer_fn+0x19a/0x620 kernel/time/timer.c:1747
 expire_timers kernel/time/timer.c:1798 [inline]
 __run_timers+0x6ef/0x960 kernel/time/timer.c:2372
 __run_timer_base kernel/time/timer.c:2384 [inline]
 __run_timer_base kernel/time/timer.c:2376 [inline]
 run_timer_base+0x114/0x190 kernel/time/timer.c:2393
 run_timer_softirq+0x1a/0x40 kernel/time/timer.c:2403
 handle_softirqs+0x219/0x8e0 kernel/softirq.c:579
 __do_softirq kernel/softirq.c:613 [inline]
 invoke_softirq kernel/softirq.c:453 [inline]
 __irq_exit_rcu+0x109/0x170 kernel/softirq.c:680
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:82
Code: 6b 6d 02 e9 83 fb 02 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa eb 07 0f 00 2d 43 79 23 00 fb f4 <c3> cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90
RSP: 0018:ffffc90000197df8 EFLAGS: 00000286
RAX: 0000000000119969 RBX: 0000000000000003 RCX: ffffffff8b869c99
RDX: 0000000000000000 RSI: ffffffff8de3046a RDI: ffffffff8c1574e0
RBP: ffffed1003c52000 R08: 0000000000000001 R09: ffffed100d4e6645
R10: ffff88806a73322b R11: 0000000000000001 R12: 0000000000000003
R13: ffff88801e290000 R14: ffffffff90a94250 R15: 0000000000000000
 arch_safe_halt arch/x86/include/asm/paravirt.h:107 [inline]
 default_idle+0x13/0x20 arch/x86/kernel/process.c:749
 default_idle_call+0x6d/0xb0 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:185 [inline]
 do_idle+0x391/0x510 kernel/sched/idle.c:325
 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:423
 start_secondary+0x21d/0x2b0 arch/x86/kernel/smpboot.c:315
 common_startup_64+0x13e/0x148
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:loopback_jiffies_timer_pos_update+0xc5a/0xfe0 sound/drivers/aloop.c:663
Code: 18 5b 5d 41 5c 41 5d 41 5e 41 5f e9 d0 22 5f 02 e8 fb 87 91 f8 48 8d 7d 48 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 3e 03 00 00 4d 89 fc 4c 2b 65 48 4c 89 7d 48 31
RSP: 0018:ffffc900006f8be0 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: ffff888025bf8600 RCX: ffffffff892a58ad
RDX: 0000000000000009 RSI: ffffffff892a6095 RDI: 0000000000000048
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000001 R12: 0000000000000002
R13: 0000000000000002 R14: 0000000000000003 R15: 00000000ffffc246
FS:  0000000000000000(0000) GS:ffff8880d6a20000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000031788000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	18 5b 5d             	sbb    %bl,0x5d(%rbx)
   3:	41 5c                	pop    %r12
   5:	41 5d                	pop    %r13
   7:	41 5e                	pop    %r14
   9:	41 5f                	pop    %r15
   b:	e9 d0 22 5f 02       	jmp    0x25f22e0
  10:	e8 fb 87 91 f8       	call   0xf8918810
  15:	48 8d 7d 48          	lea    0x48(%rbp),%rdi
  19:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  20:	fc ff df
  23:	48 89 fa             	mov    %rdi,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2e:	0f 85 3e 03 00 00    	jne    0x372
  34:	4d 89 fc             	mov    %r15,%r12
  37:	4c 2b 65 48          	sub    0x48(%rbp),%r12
  3b:	4c 89 7d 48          	mov    %r15,0x48(%rbp)
  3f:	31                   	.byte 0x31

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/27 12:36 upstream ec2df4364666 fb8f743d .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream general protection fault in loopback_jiffies_timer_pos_update
* Struck through repros no longer work on HEAD.