[syzbot] [net?] kernel BUG in skbprio_enqueue

[syzbot] [net?] kernel BUG in skbprio_enqueue

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    f6e0150b2003 Merge tag 'mtd/for-6.15' of git://git.kernel...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13a14a4c580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=46a07195688b794b
dashboard link: https://syzkaller.appspot.com/bug?extid=a3422a19b05ea96bee18
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=109e343f980000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1037abb0580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-f6e0150b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7ade4c34c9b1/vmlinux-f6e0150b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1fe37b97ec9d/bzImage-f6e0150b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a3422a19b05ea96bee18@syzkaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at net/sched/sch_skbprio.c:127!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5396 Comm: kworker/0:11 Not tainted 6.14.0-syzkaller-03565-gf6e0150b2003 #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
Workqueue: mld mld_ifc_work
RIP: 0010:skbprio_enqueue+0x1123/0x1150 net/sched/sch_skbprio.c:127
Code: 4c 89 fe e8 df 18 28 fb 4c 8b 6c 24 10 48 ba 00 00 00 00 00 fc ff df e9 87 f5 ff ff e8 76 2c b6 f7 90 0f 0b e8 6e 2c b6 f7 90 <0f> 0b 89 f9 80 e1 07 80 c1 03 38 c1 7c 88 e8 aa 58 1e f8 eb 81 89
RSP: 0018:ffffc9000d9de960 EFLAGS: 00010293
RAX: ffffffff8a0d4a22 RBX: 0000000000000002 RCX: ffff88801ed8a440
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffffffff8a0d41e8 R09: 0000000000000000
R10: ffff888043706c80 R11: ffffed10086e0d92 R12: ffff8880493798c0
R13: ffff888049378000 R14: 000000000000008e R15: ffff888049379dc0
FS:  0000000000000000(0000) GS:ffff88808c824000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb035bc92f0 CR3: 000000000e938000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 qdisc_enqueue include/net/sch_generic.h:850 [inline]
 tbf_enqueue+0x362/0x6e0 net/sched/sch_tbf.c:258
 dev_qdisc_enqueue+0x4b/0x290 net/core/dev.c:4008
 __dev_xmit_skb net/core/dev.c:4104 [inline]
 __dev_queue_xmit+0xf13/0x3f60 net/core/dev.c:4618
 dev_queue_xmit include/linux/netdevice.h:3313 [inline]
 neigh_hh_output include/net/neighbour.h:523 [inline]
 neigh_output include/net/neighbour.h:537 [inline]
 ip_finish_output2+0xcd5/0x12e0 net/ipv4/ip_output.c:236
 iptunnel_xmit+0x560/0x9c0 net/ipv4/ip_tunnel_core.c:82
 udp_tunnel_xmit_skb+0x264/0x3c0 net/ipv4/udp_tunnel_core.c:173
 geneve_xmit_skb drivers/net/geneve.c:916 [inline]
 geneve_xmit+0x2119/0x2c30 drivers/net/geneve.c:1039
 __netdev_start_xmit include/linux/netdevice.h:5151 [inline]
 netdev_start_xmit include/linux/netdevice.h:5160 [inline]
 xmit_one net/core/dev.c:3800 [inline]
 dev_hard_start_xmit+0x27a/0x7d0 net/core/dev.c:3816
 __dev_queue_xmit+0x1b80/0x3f60 net/core/dev.c:4652
 dev_queue_xmit include/linux/netdevice.h:3313 [inline]
 neigh_hh_output include/net/neighbour.h:523 [inline]
 neigh_output include/net/neighbour.h:537 [inline]
 ip6_finish_output2+0x128c/0x17e0 net/ipv6/ip6_output.c:141
 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline]
 ip6_finish_output+0x421/0x840 net/ipv6/ip6_output.c:226
 NF_HOOK+0xa0/0x440 include/linux/netfilter.h:314
 mld_sendpack+0x84a/0xdb0 net/ipv6/mcast.c:1868
 mld_send_cr net/ipv6/mcast.c:2169 [inline]
 mld_ifc_work+0x7d9/0xd90 net/ipv6/mcast.c:2702
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xac3/0x18e0 kernel/workqueue.c:3319
 worker_thread+0x870/0xd30 kernel/workqueue.c:3400
 kthread+0x7a9/0x920 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:skbprio_enqueue+0x1123/0x1150 net/sched/sch_skbprio.c:127
Code: 4c 89 fe e8 df 18 28 fb 4c 8b 6c 24 10 48 ba 00 00 00 00 00 fc ff df e9 87 f5 ff ff e8 76 2c b6 f7 90 0f 0b e8 6e 2c b6 f7 90 <0f> 0b 89 f9 80 e1 07 80 c1 03 38 c1 7c 88 e8 aa 58 1e f8 eb 81 89
RSP: 0018:ffffc9000d9de960 EFLAGS: 00010293
RAX: ffffffff8a0d4a22 RBX: 0000000000000002 RCX: ffff88801ed8a440
RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffffffff8a0d41e8 R09: 0000000000000000
R10: ffff888043706c80 R11: ffffed10086e0d92 R12: ffff8880493798c0
R13: ffff888049378000 R14: 000000000000008e R15: ffff888049379dc0
FS:  0000000000000000(0000) GS:ffff88808c824000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb035bc92f0 CR3: 000000000e938000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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Re: [syzbot] [net?] kernel BUG in skbprio_enqueue

[Cong Wang]

On Thu, Mar 27, 2025 at 03:01:29AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    f6e0150b2003 Merge tag 'mtd/for-6.15' of git://git.kernel...
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=13a14a4c580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=46a07195688b794b
> dashboard link: https://syzkaller.appspot.com/bug?extid=a3422a19b05ea96bee18
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=109e343f980000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1037abb0580000
> 
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-f6e0150b.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7ade4c34c9b1/vmlinux-f6e0150b.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/1fe37b97ec9d/bzImage-f6e0150b.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+a3422a19b05ea96bee18@syzkaller.appspotmail.com
> 
> ------------[ cut here ]------------
> kernel BUG at net/sched/sch_skbprio.c:127!

I am looking into this bug.

BTW, it is not related to my qlen_notify patchset since it is not yet
merged and this stack trace does not even involve qlen_notify.

Thanks.