Oops: general protection fault, probably for non-canonical address 0xdffffc000000000b: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000058-0x000000000000005f]
CPU: 0 UID: 0 PID: 12622 Comm: syz.4.2469 Not tainted 6.16.0-rc4-syzkaller-00324-g1f988d0788f5 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:list_empty include/linux/list.h:373 [inline]
RIP: 0010:qfq_qlen_notify+0x29/0x70 net/sched/sch_qfq.c:1422
Code: 90 f3 0f 1e fa 41 57 41 56 53 48 89 f3 49 89 fe e8 7c 35 37 f8 4c 8d 7b 58 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 ff e8 29 b8 9a f8 49 8b 07 4c 39 f8 74 1c
RSP: 0018:ffffc900040af0c8 EFLAGS: 00010202
RAX: 000000000000000b RBX: 0000000000000000 RCX: dffffc0000000000
RDX: ffffc9000bed1000 RSI: 0000000000000279 RDI: 000000000000027a
RBP: dffffc0000000000 R08: ffff88802ee99e00 R09: 0000000000000002
R10: 00000000ffffffff R11: ffffffff89892900 R12: 0000000000000000
R13: ffff8880257ac000 R14: ffff8880257ac000 R15: 0000000000000058
FS:  00007f39b62866c0(0000) GS:ffff888125c1c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f39b55b7bac CR3: 000000005558c000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 qdisc_tree_reduce_backlog+0x29c/0x480 net/sched/sch_api.c:811
 codel_change+0x859/0xae0 net/sched/sch_codel.c:153
 codel_init+0x1f7/0x3e0 net/sched/sch_codel.c:172
 qdisc_create+0x7ac/0xea0 net/sched/sch_api.c:1324
 __tc_modify_qdisc net/sched/sch_api.c:1749 [inline]
 tc_modify_qdisc+0x1426/0x2010 net/sched/sch_api.c:1813
 rtnetlink_rcv_msg+0x779/0xb70 net/core/rtnetlink.c:6953
 netlink_rcv_skb+0x208/0x470 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x75b/0x8d0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:727
 ____sys_sendmsg+0x505/0x830 net/socket.c:2566
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
 __sys_sendmsg net/socket.c:2652 [inline]
 __do_sys_sendmsg net/socket.c:2657 [inline]
 __se_sys_sendmsg net/socket.c:2655 [inline]
 __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f39b538e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f39b6286038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f39b55b5fa0 RCX: 00007f39b538e929
RDX: 0000000000000800 RSI: 0000200000000100 RDI: 0000000000000008
RBP: 00007f39b5410b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f39b55b5fa0 R15: 00007f39b56dfa28
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:list_empty include/linux/list.h:373 [inline]
RIP: 0010:qfq_qlen_notify+0x29/0x70 net/sched/sch_qfq.c:1422
Code: 90 f3 0f 1e fa 41 57 41 56 53 48 89 f3 49 89 fe e8 7c 35 37 f8 4c 8d 7b 58 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 ff e8 29 b8 9a f8 49 8b 07 4c 39 f8 74 1c
RSP: 0018:ffffc900040af0c8 EFLAGS: 00010202
RAX: 000000000000000b RBX: 0000000000000000 RCX: dffffc0000000000
RDX: ffffc9000bed1000 RSI: 0000000000000279 RDI: 000000000000027a
RBP: dffffc0000000000 R08: ffff88802ee99e00 R09: 0000000000000002
R10: 00000000ffffffff R11: ffffffff89892900 R12: 0000000000000000
R13: ffff8880257ac000 R14: ffff8880257ac000 R15: 0000000000000058
FS:  00007f39b62866c0(0000) GS:ffff888125c1c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f39b55b7bac CR3: 000000005558c000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	90                   	nop
   1:	f3 0f 1e fa          	endbr64
   5:	41 57                	push   %r15
   7:	41 56                	push   %r14
   9:	53                   	push   %rbx
   a:	48 89 f3             	mov    %rsi,%rbx
   d:	49 89 fe             	mov    %rdi,%r14
  10:	e8 7c 35 37 f8       	call   0xf8373591
  15:	4c 8d 7b 58          	lea    0x58(%rbx),%r15
  19:	4c 89 f8             	mov    %r15,%rax
  1c:	48 c1 e8 03          	shr    $0x3,%rax
  20:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  27:	fc ff df
* 2a:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	4c 89 ff             	mov    %r15,%rdi
  33:	e8 29 b8 9a f8       	call   0xf89ab861
  38:	49 8b 07             	mov    (%r15),%rax
  3b:	4c 39 f8             	cmp    %r15,%rax
  3e:	74 1c                	je     0x5c