syzbot


BUG: unable to handle kernel NULL pointer dereference in loopback_jiffies_timer_pos_update

Status: moderation: reported on 2022/09/23 13:54
Reported-by: syzbot+e2502ffc2b77b3f4c09d@syzkaller.appspotmail.com
First crash: 69d, last: 69d

Sample crash report:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000048
Mem abort info:
  ESR = 0x0000000096000005
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x05: level 1 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000005
  CM = 0, WnR = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=00000001321e5000
[0000000000000048] pgd=0800000107f8e003, p4d=0800000107f8e003, pud=0000000000000000
Internal error: Oops: 96000005 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 0 Comm: swapper/1 Not tainted 6.0.0-rc4-syzkaller-17255-ga6b443748715 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
pstate: 004000c5 (nzcv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : loopback_jiffies_timer_pos_update+0x8c/0x5fc sound/drivers/aloop.c:618
lr : loopback_jiffies_timer_pos_update+0x88/0x5fc sound/drivers/aloop.c:618
sp : ffff80000800bd80
x29: ffff80000800bd80 x28: dead000000000122 x27: ffff80000800bea8
x26: 0000000003c00001 x25: 0000000000000000 x24: ffff80000b06bfcc
x23: 000000000000000e x22: ffff80000d2bb000 x21: ffff0000e2674b00
x20: 0000000000000000 x19: 0000000000000003 x18: 0000000000000118
x17: ffff80000c00d6bc x16: ffff80000db78658 x15: ffff0000c02dcf80
x14: 00000000000000f0 x13: 00000000ffffffff x12: ffff0000c02dcf80
x11: ff8080000b06b9bc x10: 0000000000000000 x9 : ffff80000b06b9bc
x8 : 000000010002aa0f x7 : ffff80000b06bff4 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000001 x1 : 0000000000000002 x0 : 0000000000000000
Call trace:
 loopback_jiffies_timer_pos_update+0x8c/0x5fc sound/drivers/aloop.c:618
 loopback_jiffies_timer_function+0x38/0x1f4 sound/drivers/aloop.c:661
 call_timer_fn+0x90/0x144 kernel/time/timer.c:1474
 expire_timers kernel/time/timer.c:1519 [inline]
 __run_timers+0x280/0x374 kernel/time/timer.c:1790
 run_timer_softirq+0x34/0x5c kernel/time/timer.c:1803
 _stext+0x168/0x37c
 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:79
 call_on_irq_stack+0x2c/0x54
 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:84
 invoke_softirq+0x70/0xbc kernel/softirq.c:452
 __irq_exit_rcu+0xf0/0x140 kernel/softirq.c:650
 irq_exit_rcu+0x10/0x40 kernel/softirq.c:662
 __el1_irq arch/arm64/kernel/entry-common.c:459 [inline]
 el1_interrupt+0x38/0x68 arch/arm64/kernel/entry-common.c:473
 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:478
 el1h_64_irq+0x64/0x68
 arch_local_irq_enable arch/arm64/include/asm/irqflags.h:35 [inline]
 raw_spin_rq_unlock_irq kernel/sched/sched.h:1367 [inline]
 finish_lock_switch+0x9c/0xe8 kernel/sched/core.c:4942
 finish_task_switch+0x98/0x270 kernel/sched/core.c:5060
 context_switch kernel/sched/core.c:5185 [inline]
 __schedule+0x418/0x5a0 kernel/sched/core.c:6494
 schedule_idle+0x24/0x44 kernel/sched/core.c:6598
 do_idle+0x29c/0x2d8 kernel/sched/idle.c:331
 cpu_startup_entry+0x24/0x28 kernel/sched/idle.c:400
 secondary_start_kernel+0x154/0x17c arch/arm64/kernel/smp.c:265
 __secondary_switched+0xb0/0xb4
Code: aa1f03f6 14000006 9748d5e5 f94102c8 (f9402689) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	aa1f03f6 	mov	x22, xzr
   4:	14000006 	b	0x1c
   8:	9748d5e5 	bl	0xfffffffffd23579c
   c:	f94102c8 	ldr	x8, [x22, #512]
* 10:	f9402689 	ldr	x9, [x20, #72] <-- trapping instruction

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-gce-arm64 2022/09/19 13:47 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci a6b443748715 dd9a85ff .config log report info BUG: unable to handle kernel NULL pointer dereference in loopback_jiffies_timer_pos_update
* Struck through repros no longer work on HEAD.