Oops: general protection fault, probably for non-canonical address 0xdffffc0000000004: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
CPU: 1 UID: 0 PID: 10045 Comm: syz.2.1121 Not tainted 6.16.0-rc5-syzkaller-00038-g733923397fd9 #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:qdisc_tree_reduce_backlog+0x1cb/0x500 net/sched/sch_api.c:806
Code: 4d 8b 67 18 49 8d 7c 24 08 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 ff 02 00 00 4d 8b 74 24 08 4d 8d 66 20 4c 89 e0 48 c1 e8 03 <80> 3c 18 00 0f 85 1a 03 00 00 49 83 7e 20 00 74 48 e8 cf cf 36 f8
RSP: 0018:ffffc90005f77348 EFLAGS: 00010202
RAX: 0000000000000004 RBX: dffffc0000000000 RCX: ffffc90007571000
RDX: 0000000000080000 RSI: ffffffff898526ec RDI: ffffffff90aa1808
RBP: 00000000000afff2 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000020
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88802c441800
FS:  00007f72c05ad6c0(0000) GS:ffff8880d6816000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f72c05acf98 CR3: 000000005c5cc000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 codel_change+0x6d9/0xc90 net/sched/sch_codel.c:153
 codel_init+0x2e6/0x430 net/sched/sch_codel.c:172
 qdisc_create+0x457/0xfc0 net/sched/sch_api.c:1324
 __tc_modify_qdisc net/sched/sch_api.c:1749 [inline]
 tc_modify_qdisc+0x12bb/0x2130 net/sched/sch_api.c:1813
 rtnetlink_rcv_msg+0x3c9/0xe90 net/core/rtnetlink.c:6953
 netlink_rcv_skb+0x158/0x420 net/netlink/af_netlink.c:2534
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x53a/0x7f0 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1883
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg net/socket.c:727 [inline]
 ____sys_sendmsg+0xa95/0xc70 net/socket.c:2566
 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620
 __sys_sendmsg+0x16d/0x220 net/socket.c:2652
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f72bf78e929
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:00007f72c05ad038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f72bf9b5fa0 RCX: 00007f72bf78e929
RDX: 0000000000000800 RSI: 0000200000000100 RDI: 0000000000000004
RBP: 00007f72bf810b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f72bf9b5fa0 R15: 00007ffc26635778
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:qdisc_tree_reduce_backlog+0x1cb/0x500 net/sched/sch_api.c:806
Code: 4d 8b 67 18 49 8d 7c 24 08 48 89 f8 48 c1 e8 03 80 3c 18 00 0f 85 ff 02 00 00 4d 8b 74 24 08 4d 8d 66 20 4c 89 e0 48 c1 e8 03 <80> 3c 18 00 0f 85 1a 03 00 00 49 83 7e 20 00 74 48 e8 cf cf 36 f8
RSP: 0018:ffffc90005f77348 EFLAGS: 00010202
RAX: 0000000000000004 RBX: dffffc0000000000 RCX: ffffc90007571000
RDX: 0000000000080000 RSI: ffffffff898526ec RDI: ffffffff90aa1808
RBP: 00000000000afff2 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000020
R13: 0000000000000000 R14: 0000000000000000 R15: ffff88802c441800
FS:  00007f72c05ad6c0(0000) GS:ffff8880d6816000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f72c05acf98 CR3: 000000005c5cc000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
   0:	4d 8b 67 18          	mov    0x18(%r15),%r12
   4:	49 8d 7c 24 08       	lea    0x8(%r12),%rdi
   9:	48 89 f8             	mov    %rdi,%rax
   c:	48 c1 e8 03          	shr    $0x3,%rax
  10:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1)
  14:	0f 85 ff 02 00 00    	jne    0x319
  1a:	4d 8b 74 24 08       	mov    0x8(%r12),%r14
  1f:	4d 8d 66 20          	lea    0x20(%r14),%r12
  23:	4c 89 e0             	mov    %r12,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1) <-- trapping instruction
  2e:	0f 85 1a 03 00 00    	jne    0x34e
  34:	49 83 7e 20 00       	cmpq   $0x0,0x20(%r14)
  39:	74 48                	je     0x83
  3b:	e8 cf cf 36 f8       	call   0xf836d00f