syzbot
BUG: unable to handle kernel paging request in fq_codel_enqueue
Status:
auto-obsoleted due to no activity on 2025/11/29 22:34
Reported-by: syzbot+339e7ece7243e5f5ff77@syzkaller.appspotmail.com
First crash: 380d, last: 330d
Sample crash report:
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
* Struck through repros no longer work on HEAD.