syzbot


BUG: unable to handle kernel paging request in fq_codel_enqueue (2)

Status: upstream: reported on 2026/04/29 00:07
Reported-by: syzbot+3ac39748891ee2433e44@syzkaller.appspotmail.com
First crash: 23h18m, last: 23h18m
Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 BUG: unable to handle kernel paging request in fq_codel_enqueue 8 13 221d 271d 0/3 auto-obsoleted due to no activity on 2025/11/29 22:34
upstream general protection fault in fq_codel_enqueue (3) net 2 C inconclusive 5 1397d 1643d 22/29 fixed on 2023/02/24 13:50
linux-4.19 general protection fault in fq_codel_enqueue (2) 2 C error 14 1338d 2070d 0/1 upstream: reported C repro on 2020/08/28 22:42
linux-5.15 general protection fault in fq_codel_enqueue (2) 2 1 21h57m 21h57m 0/3 upstream: reported on 2026/04/29 01:27
android-5-10 general protection fault in fq_codel_enqueue (2) 2 2 737d 739d 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 767d 767d 0/2 auto-obsoleted due to no activity on 2024/06/21 01:28
linux-6.1 general protection fault in fq_codel_enqueue 2 1 104d 104d 0/3 auto-obsoleted due to no activity on 2026/04/25 11:32
linux-4.14 general protection fault in fq_codel_enqueue 2 C inconclusive 6 1600d 2193d 0/1 upstream: reported C repro on 2020/04/27 21:56
linux-5.15 general protection fault in fq_codel_enqueue 2 3 139d 266d 0/3 auto-obsoleted due to no activity on 2026/03/21 20:16
upstream general protection fault in fq_codel_enqueue (2) 2 C done 34 1670d 2070d 0/29 closed as invalid on 2021/10/07 21:22
android-5-10 general protection fault in fq_codel_enqueue 2 1 1372d 1372d 0/2 auto-obsoleted due to no activity on 2022/10/25 22:19

Sample crash report:
device syzkaller0 entered promiscuous mode
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: 7358 Comm: syz.2.977 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
pstate: 82400005 (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+0x870/0x10d8 net/sched/sch_fq_codel.c:230
lr : fq_codel_drop net/sched/sch_fq_codel.c:162 [inline]
lr : fq_codel_enqueue+0x7e4/0x10d8 net/sched/sch_fq_codel.c:230
sp : ffff800021bb7180
x29: ffff800021bb7280 x28: 0000000000000000 x27: 0000000000000000
x26: 0000000000000000 x25: 0000000000000001 x24: ffff000104f40000
x23: 0000000000000000 x22: 0000000000000000 x21: 0000000000000001
x20: ffff0000da8c3ad0 x19: 0000000000000000 x18: 0000000000000000
x17: 0000000000420050 x16: ffff8000082d92bc x15: 0000000000000002
x14: 0000000000000003 x13: 1ffff00002a44071 x12: 0000000000080000
x11: 000000000000131e x10: dfff800000000000 x9 : 1fffe000209e8000
x8 : 0000000000000000 x7 : ffff8000083c1bd4 x6 : 0000000000000000
x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000
x2 : ffff0000da8c3b28 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+0x870/0x10d8 net/sched/sch_fq_codel.c:230
 qdisc_enqueue include/net/sch_generic.h:854 [inline]
 netem_dequeue+0xa78/0x1080 net/sched/sch_netem.c:737
 dequeue_skb net/sched/sch_generic.c:295 [inline]
 qdisc_restart net/sched/sch_generic.c:400 [inline]
 __qdisc_run+0x1cc/0x133c net/sched/sch_generic.c:418
 __dev_xmit_skb net/core/dev.c:3995 [inline]
 __dev_queue_xmit+0xc40/0x3118 net/core/dev.c:4337
 dev_queue_xmit+0x24/0x34 include/linux/netdevice.h:3051
 packet_snd net/packet/af_packet.c:3127 [inline]
 packet_sendmsg+0x2f9c/0x3fd0 net/packet/af_packet.c:3158
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 __sys_sendto+0x324/0x440 net/socket.c:2152
 __do_sys_sendto net/socket.c:2164 [inline]
 __se_sys_sendto net/socket.c:2160 [inline]
 __arm64_sys_sendto+0xd8/0xf8 net/socket.c:2160
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 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: d2d0000a f2fbffea f9400317 d343fee8 (386a6908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	d2d0000a 	mov	x10, #0x800000000000        	// #140737488355328
   4:	f2fbffea 	movk	x10, #0xdfff, lsl #48
   8:	f9400317 	ldr	x23, [x24]
   c:	d343fee8 	lsr	x8, x23, #3
* 10:	386a6908 	ldrb	w8, [x8, x10] <-- trapping instruction

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/29 00:06 linux-6.1.y 7c87defbd336 95008c03 .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
* Struck through repros no longer work on HEAD.