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: 1 PID: 21 Comm: ksoftirqd/1 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 : ffff80001c937320
x29: ffff80001c937430 x28: 0000000000000000 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000001 x24: ffff0000ea2a0000
x23: 0000000000000000 x22: ffff0000c36fcad0 x21: ffff80001c937620
x20: dfff800000000000 x19: 0000000000000000 x18: 000000006bbcf466
x17: 00000000ffff0000 x16: ffff8000082d22d4 x15: 0000000000000000
x14: 0000000000000003 x13: 1ffff00002a180b1 x12: 0000000000ff0100
x11: ff0080000ffaca10 x10: 0000000000000000 x9 : 1fffe0001d454000
x8 : 0000000000000000 x7 : ffff8000083b9864 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : ffff0000c36fcb28 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]
 tbf_enqueue+0x2dc/0x610 net/sched/sch_tbf.c:257
 dev_qdisc_enqueue+0x5c/0x38c net/core/dev.c:3875
 __dev_xmit_skb net/core/dev.c:3964 [inline]
 __dev_queue_xmit+0xad0/0x309c 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
 run_ksoftirqd+0x7c/0x2a0 kernel/softirq.c:963
 smpboot_thread_fn+0x4b0/0x964 kernel/smpboot.c:164
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:850
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