syzbot


BUG: unable to handle kernel paging request in fq_codel_enqueue

Status: upstream: reported on 2025/08/01 20:04
Reported-by: syzbot+339e7ece7243e5f5ff77@syzkaller.appspotmail.com
First crash: 27d, last: 2d01h
Similar bugs (10)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream general protection fault in fq_codel_enqueue (3) net 2 C inconclusive 5 1153d 1399d 22/29 fixed on 2023/02/24 13:50
linux-4.19 general protection fault in fq_codel_enqueue (2) 2 C error 14 1094d 1826d 0/1 upstream: reported C repro on 2020/08/28 22:42
android-5-10 general protection fault in fq_codel_enqueue (2) 2 2 493d 495d 0/2 auto-obsoleted due to no activity on 2024/07/20 23:55
android-5-15 general protection fault in fq_codel_enqueue 2 1 523d 523d 0/2 auto-obsoleted due to no activity on 2024/06/21 01:28
linux-4.14 general protection fault in fq_codel_enqueue 2 C inconclusive 6 1356d 1949d 0/1 upstream: reported C repro on 2020/04/27 21:56
linux-5.15 general protection fault in fq_codel_enqueue 2 1 22d 22d 0/3 upstream: reported on 2025/08/06 04:45
upstream general protection fault in fq_codel_enqueue (2) 2 C done 34 1426d 1826d 0/29 closed as invalid on 2021/10/07 21:22
android-5-10 general protection fault in fq_codel_enqueue 2 1 1128d 1128d 0/2 auto-obsoleted due to no activity on 2022/10/25 22:19
linux-4.19 general protection fault in fq_codel_enqueue 2 C done 5 1924d 1952d 1/1 fixed on 2020/06/21 14:03
upstream general protection fault in fq_codel_enqueue net 2 C done 25 1872d 1957d 15/29 fixed on 2020/07/17 17:58

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: 0 PID: 4297 Comm: udevd Not tainted 6.1.147-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
pstate: 40400005 (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 : ffff8000080074a0
x29: ffff8000080075a0 x28: 0000000000000000 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000001 x24: ffff0000d9965c00
x23: 0000000000000000 x22: ffff0000dce652d0 x21: ffff800008007860
x20: dfff800000000000 x19: 0000000000000000 x18: 00000000ae1f9abe
x17: ffff8000181e7000 x16: ffff8000082d2374 x15: ffff800017cc7fc0
x14: ffff0000d3f44218 x13: 1ffff00002a160b1 x12: 0000000000ff0100
x11: ff0080000ff9d370 x10: 0000000000000000 x9 : 1fffe0001b32cb80
x8 : 0000000000000000 x7 : ffff8000083b9874 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : ffff0000dce65328 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]
 sfb_enqueue+0x794/0x1294 net/sched/sch_sfb.c:405
 dev_qdisc_enqueue+0x5c/0x38c net/core/dev.c:3863
 __dev_xmit_skb net/core/dev.c:3952 [inline]
 __dev_queue_xmit+0xad0/0x309c net/core/dev.c:4300
 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+0x24/0x30 arch/arm64/kernel/entry.S:849
 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_restore arch/arm64/include/asm/irqflags.h:122 [inline]
 seqcount_lockdep_reader_access include/linux/seqlock.h:104 [inline]
 set_root+0x204/0x48c fs/namei.c:945
 nd_jump_root+0x26c/0x3cc fs/namei.c:966
 path_init+0x37c/0x1120 fs/namei.c:2389
 path_openat+0x12c/0x2680 fs/namei.c:3778
 do_filp_open+0x174/0x344 fs/namei.c:3810
 do_sys_openat2+0x128/0x3d8 fs/open.c:1318
 do_sys_open fs/open.c:1334 [inline]
 __do_sys_openat fs/open.c:1350 [inline]
 __se_sys_openat fs/open.c:1345 [inline]
 __arm64_sys_openat+0x120/0x154 fs/open.c:1345
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: aa1803e0 9624e4c0 f9400317 d343fee8 (38746908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	aa1803e0 	mov	x0, x24
   4:	9624e4c0 	bl	0xfffffffff8939304
   8:	f9400317 	ldr	x23, [x24]
   c:	d343fee8 	lsr	x8, x23, #3
* 10:	38746908 	ldrb	w8, [x8, x20] <-- trapping instruction

Crashes (9):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/08/01 20:04 linux-6.1.y 3594f306da12 40127d41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in fq_codel_enqueue
2025/08/01 20:04 linux-6.1.y 3594f306da12 40127d41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in fq_codel_enqueue
2025/08/26 21:56 linux-6.1.y 0bc96de781b4 e12e5ba4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in fq_codel_enqueue
2025/08/22 08:13 linux-6.1.y 0bc96de781b4 bf27483f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in fq_codel_enqueue
2025/08/20 19:30 linux-6.1.y 0bc96de781b4 0b9605c8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in fq_codel_enqueue
2025/08/12 22:44 linux-6.1.y 3594f306da12 22ec1469 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in fq_codel_enqueue
2025/08/01 21:00 linux-6.1.y 3594f306da12 40127d41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in fq_codel_enqueue
2025/08/01 20:58 linux-6.1.y 3594f306da12 40127d41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in fq_codel_enqueue
2025/08/01 20:57 linux-6.1.y 3594f306da12 40127d41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in fq_codel_enqueue
* Struck through repros no longer work on HEAD.