syzbot


general protection fault in htb_qlen_notify

Status: upstream: reported C repro on 2025/07/03 08:17
Subsystems: net
[Documentation on labels]
Reported-by: syzbot+d8b58d7b0ad89a678a16@syzkaller.appspotmail.com
First crash: 3d04h, last: 1h22m
Cause bisection: introduced by (bisect log) :
commit 103406b38c600fec1fe375a77b27d87e314aea09
Author: Lion Ackermann <nnamrec@gmail.com>
Date: Mon Jun 30 13:27:30 2025 +0000

  net/sched: Always pass notifications when child class becomes empty

Crash: BUG: unable to handle kernel NULL pointer dereference in htb_qlen_notify (log)
Repro: C syz .config
  
Discussions (2)
Title Replies (including bot) Last reply
[PATCH net] net/sched: Abort __tc_modify_qdisc if parent class does not exist 3 (3) 2025/07/05 14:03
[syzbot] [net?] general protection fault in htb_qlen_notify 3 (7) 2025/07/05 05:43
Last patch testing requests (1)
Created Duration User Patch Repo Result
2025/07/03 21:06 1h40m victor@mojatatu.com patch net OK log

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000035: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x00000000000001a8-0x00000000000001af]
CPU: 0 UID: 0 PID: 6084 Comm: syz.0.16 Not tainted 6.16.0-rc3-syzkaller-00144-gbd475eeaaf3c #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:htb_deactivate net/sched/sch_htb.c:613 [inline]
RIP: 0010:htb_qlen_notify+0x31/0xc0 net/sched/sch_htb.c:1489
Code: 41 56 41 55 41 54 53 49 89 f6 49 89 ff 49 bc 00 00 00 00 00 fc ff df e8 3d c6 46 f8 49 8d 9e a8 01 00 00 49 89 dd 49 c1 ed 03 <43> 0f b6 44 25 00 84 c0 75 4d 8b 2b 31 ff 89 ee e8 5a ca 46 f8 85
RSP: 0018:ffffc90003446fb0 EFLAGS: 00010206
RAX: ffffffff89798833 RBX: 00000000000001a8 RCX: ffff88802ffb0000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888072130000
RBP: dffffc0000000000 R08: ffff88802ffb0000 R09: 0000000000000002
R10: 00000000ffffffff R11: ffffffff89798810 R12: dffffc0000000000
R13: 0000000000000035 R14: 0000000000000000 R15: ffff888072130000
FS:  00007fbd3d5fe6c0(0000) GS:ffff888125c50000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f92b51d2440 CR3: 000000007ce86000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 qdisc_tree_reduce_backlog+0x29c/0x480 net/sched/sch_api.c:811
 fq_change+0x1519/0x1f50 net/sched/sch_fq.c:1147
 fq_init+0x699/0x960 net/sched/sch_fq.c:1201
 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: 0033:0x7fbd3e38e929
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:00007fbd3d5fe038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007fbd3e5b5fa0 RCX: 00007fbd3e38e929
RDX: 0000000000044080 RSI: 0000200000000040 RDI: 0000000000000006
RBP: 00007fbd3e410b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fbd3e5b5fa0 R15: 00007ffd70284448
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:htb_deactivate net/sched/sch_htb.c:613 [inline]
RIP: 0010:htb_qlen_notify+0x31/0xc0 net/sched/sch_htb.c:1489
Code: 41 56 41 55 41 54 53 49 89 f6 49 89 ff 49 bc 00 00 00 00 00 fc ff df e8 3d c6 46 f8 49 8d 9e a8 01 00 00 49 89 dd 49 c1 ed 03 <43> 0f b6 44 25 00 84 c0 75 4d 8b 2b 31 ff 89 ee e8 5a ca 46 f8 85
RSP: 0018:ffffc90003446fb0 EFLAGS: 00010206
RAX: ffffffff89798833 RBX: 00000000000001a8 RCX: ffff88802ffb0000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888072130000
RBP: dffffc0000000000 R08: ffff88802ffb0000 R09: 0000000000000002
R10: 00000000ffffffff R11: ffffffff89798810 R12: dffffc0000000000
R13: 0000000000000035 R14: 0000000000000000 R15: ffff888072130000
FS:  00007fbd3d5fe6c0(0000) GS:ffff888125c50000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f92b51d2440 CR3: 000000007ce86000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	41 56                	push   %r14
   2:	41 55                	push   %r13
   4:	41 54                	push   %r12
   6:	53                   	push   %rbx
   7:	49 89 f6             	mov    %rsi,%r14
   a:	49 89 ff             	mov    %rdi,%r15
   d:	49 bc 00 00 00 00 00 	movabs $0xdffffc0000000000,%r12
  14:	fc ff df
  17:	e8 3d c6 46 f8       	call   0xf846c659
  1c:	49 8d 9e a8 01 00 00 	lea    0x1a8(%r14),%rbx
  23:	49 89 dd             	mov    %rbx,%r13
  26:	49 c1 ed 03          	shr    $0x3,%r13
* 2a:	43 0f b6 44 25 00    	movzbl 0x0(%r13,%r12,1),%eax <-- trapping instruction
  30:	84 c0                	test   %al,%al
  32:	75 4d                	jne    0x81
  34:	8b 2b                	mov    (%rbx),%ebp
  36:	31 ff                	xor    %edi,%edi
  38:	89 ee                	mov    %ebp,%esi
  3a:	e8 5a ca 46 f8       	call   0xf846ca99
  3f:	85                   	.byte 0x85

Crashes (94):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/03 17:46 net bd475eeaaf3c 115ceea7 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/03 14:14 net bd475eeaaf3c 115ceea7 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/03 11:32 net bd475eeaaf3c 115ceea7 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/06 09:00 upstream 05df91921da6 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/06 07:05 upstream 05df91921da6 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/06 05:53 upstream 05df91921da6 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/06 03:28 upstream 05df91921da6 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/05 22:45 upstream 05df91921da6 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/05 18:26 upstream a79a588fc176 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/05 14:41 upstream a79a588fc176 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/05 08:34 upstream a79a588fc176 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/05 04:22 upstream 4c06e63b9203 d869b261 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/05 02:08 upstream 4c06e63b9203 d869b261 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-selinux-root general protection fault in htb_qlen_notify
2025/07/05 00:01 upstream 4c06e63b9203 d869b261 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-badwrites-root general protection fault in htb_qlen_notify
2025/07/04 22:49 upstream 4c06e63b9203 d869b261 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/04 20:52 upstream 4c06e63b9203 d869b261 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root general protection fault in htb_qlen_notify
2025/07/04 17:23 upstream 4c06e63b9203 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/04 16:07 upstream 4c06e63b9203 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/04 11:15 upstream 17bbde2e1716 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce general protection fault in htb_qlen_notify
2025/07/04 05:22 upstream 17bbde2e1716 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root general protection fault in htb_qlen_notify
2025/07/04 05:22 upstream 17bbde2e1716 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root general protection fault in htb_qlen_notify
2025/07/05 10:58 upstream a79a588fc176 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 general protection fault in htb_qlen_notify
2025/07/04 07:00 upstream 17bbde2e1716 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 general protection fault in htb_qlen_notify
2025/07/04 04:33 upstream 17bbde2e1716 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 general protection fault in htb_qlen_notify
2025/07/04 04:33 upstream 17bbde2e1716 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 general protection fault in htb_qlen_notify
2025/07/04 02:05 upstream 17bbde2e1716 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 general protection fault in htb_qlen_notify
2025/07/04 01:57 upstream 17bbde2e1716 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 general protection fault in htb_qlen_notify
2025/07/04 01:53 upstream 17bbde2e1716 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 general protection fault in htb_qlen_notify
2025/07/03 21:57 upstream 17bbde2e1716 115ceea7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 general protection fault in htb_qlen_notify
2025/07/03 21:49 upstream 17bbde2e1716 115ceea7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-386 general protection fault in htb_qlen_notify
2025/07/05 07:05 upstream c435a4f487e8 4f67c4ae .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream general protection fault in htb_qlen_notify
2025/07/04 22:05 upstream c435a4f487e8 d869b261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream general protection fault in htb_qlen_notify
2025/07/04 16:01 upstream 4c06e63b9203 d869b261 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root general protection fault in htb_qlen_notify
2025/07/04 15:56 upstream 4c06e63b9203 d869b261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream general protection fault in htb_qlen_notify
2025/07/04 15:55 upstream 4c06e63b9203 d869b261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream general protection fault in htb_qlen_notify
2025/07/04 15:55 upstream 4c06e63b9203 d869b261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream general protection fault in htb_qlen_notify
2025/07/04 16:07 upstream 4c06e63b9203 d869b261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 general protection fault in htb_qlen_notify
2025/07/04 16:07 upstream 4c06e63b9203 d869b261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 general protection fault in htb_qlen_notify
2025/07/04 16:07 upstream 4c06e63b9203 d869b261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 general protection fault in htb_qlen_notify
2025/07/04 16:07 upstream 4c06e63b9203 d869b261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 general protection fault in htb_qlen_notify
2025/07/04 16:06 upstream 4c06e63b9203 d869b261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 general protection fault in htb_qlen_notify
2025/07/04 19:06 net b9fd9888a565 d869b261 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/04 15:57 net b9fd9888a565 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/04 15:56 net b9fd9888a565 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/04 15:05 net b9fd9888a565 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/04 11:37 net 223e2288f4b8 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/04 07:53 net 223e2288f4b8 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/03 23:46 net 223e2288f4b8 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/03 23:45 net 223e2288f4b8 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/03 23:45 net 223e2288f4b8 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/03 07:30 net bd475eeaaf3c 0cd59a8f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/03 06:31 net bd475eeaaf3c 0cd59a8f .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-this-kasan-gce general protection fault in htb_qlen_notify
2025/07/05 20:22 net-next 6b9fd8857b9f 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce general protection fault in htb_qlen_notify
2025/07/05 17:08 net-next 6b9fd8857b9f 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce general protection fault in htb_qlen_notify
2025/07/05 03:14 net-next 6b9fd8857b9f d869b261 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce general protection fault in htb_qlen_notify
2025/07/04 15:56 net-next 6b9fd8857b9f 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce general protection fault in htb_qlen_notify
2025/07/04 15:55 net-next 6b9fd8857b9f 76ad128c .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-net-kasan-gce general protection fault in htb_qlen_notify
2025/07/03 12:57 linux-next 8d6c58332c7a 115ceea7 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root general protection fault in htb_qlen_notify
2025/07/05 08:58 upstream a79a588fc176 4f67c4ae .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu2-arm32 BUG: unable to handle kernel NULL pointer dereference in htb_qlen_notify
* Struck through repros no longer work on HEAD.