syzbot

Unable to handle kernel paging request at virtual address dfff800000000000
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006
  CM = 0, WnR = 0
[dfff800000000000] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
pstate: 42400005 (nZcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : dequeue_head net/sched/sch_fq_codel.c:120 [inline]
pc : fq_codel_drop net/sched/sch_fq_codel.c:168 [inline]
pc : fq_codel_enqueue+0x79c/0xf38 net/sched/sch_fq_codel.c:230
lr : fq_codel_drop net/sched/sch_fq_codel.c:162 [inline]
lr : fq_codel_enqueue+0x728/0xf38 net/sched/sch_fq_codel.c:230
sp : ffff8000080073a0
x29: ffff8000080074a0 x28: 0000000000000000 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000001 x24: ffff000106a00000
x23: 0000000000000000 x22: ffff0000c3048ad0 x21: ffff800008007600
x20: dfff800000000000 x19: 0000000000000000 x18: 00000000ff8d3a60
x17: 0000000000c200d0 x16: ffff8000082d22d4 x15: 0000000000000000
x14: 0000000000000003 x13: 1ffff00002a180b1 x12: 0000000000ff0100
x11: ff0080000ffaca10 x10: 0000000000000000 x9 : 1fffe00020d40000
x8 : 0000000000000000 x7 : ffff8000083b9864 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : ffff0000c3048b28 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
 dequeue_head net/sched/sch_fq_codel.c:120 [inline]
 fq_codel_drop net/sched/sch_fq_codel.c:168 [inline]
 fq_codel_enqueue+0x79c/0xf38 net/sched/sch_fq_codel.c:230
 qdisc_enqueue include/net/sch_generic.h:816 [inline]
 netem_dequeue+0xa74/0x107c net/sched/sch_netem.c:737
 try_bulk_dequeue_skb_slow net/sched/sch_generic.c:211 [inline]
 dequeue_skb net/sched/sch_generic.c:298 [inline]
 qdisc_restart net/sched/sch_generic.c:397 [inline]
 __qdisc_run+0x224/0x1368 net/sched/sch_generic.c:415
 __dev_xmit_skb net/core/dev.c:3970 [inline]
 __dev_queue_xmit+0xc18/0x309c net/core/dev.c:4312
 dev_queue_xmit include/linux/netdevice.h:3051 [inline]
 tipc_l2_send_msg+0x29c/0x35c net/tipc/bearer.c:518
 tipc_bearer_xmit_skb+0x244/0x384 net/tipc/bearer.c:577
 tipc_disc_timeout+0x4c8/0x608 net/tipc/discover.c:338
 call_timer_fn+0x1b8/0x964 kernel/time/timer.c:1504
 expire_timers kernel/time/timer.c:1549 [inline]
 __run_timers+0x460/0x6bc kernel/time/timer.c:1820
 run_timer_softirq+0x7c/0x114 kernel/time/timer.c:1833
 handle_softirqs+0x318/0xc6c kernel/softirq.c:596
 __do_softirq+0x14/0x20 kernel/softirq.c:630
 ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:80
 call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:897
 do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:85
 invoke_softirq kernel/softirq.c:477 [inline]
 __irq_exit_rcu+0x23c/0x43c kernel/softirq.c:679
 irq_exit_rcu+0x14/0x84 kernel/softirq.c:691
 __el1_irq arch/arm64/kernel/entry-common.c:472 [inline]
 el1_interrupt+0x38/0x54 arch/arm64/kernel/entry-common.c:486
 el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:491
 el1h_64_irq+0x64/0x68 arch/arm64/kernel/entry.S:581
 arch_local_irq_enable+0xc/0x18 arch/arm64/include/asm/irqflags.h:35
 default_idle_call+0x68/0xdc kernel/sched/idle.c:109
 cpuidle_idle_call kernel/sched/idle.c:191 [inline]
 do_idle+0x1d8/0x4bc kernel/sched/idle.c:303
 cpu_startup_entry+0x5c/0x74 kernel/sched/idle.c:401
 rest_init+0x2d4/0x2f0 init/main.c:733
 start_kernel+0x0/0x554 init/main.c:893
 start_kernel+0x4a4/0x554 init/main.c:1140
 __primary_switched+0xb8/0xc0 arch/arm64/kernel/head.S:468
Code: aa1803e0 9624a7a8 f9400317 d343fee8 (38746908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	aa1803e0 	mov	x0, x24
   4:	9624a7a8 	bl	0xfffffffff8929ea4
   8:	f9400317 	ldr	x23, [x24]
   c:	d343fee8 	lsr	x8, x23, #3
* 10:	38746908 	ldrb	w8, [x8, x20] <-- trapping instruction