linux-kernel - [syzbot] [kvm?] [net?] [virt?] WARNING in virtio_transport_send_pkt

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Message-ID: <6928fe78.a70a0220.d98e3.012a.GAE@google.com>
Date: Thu, 27 Nov 2025 17:44:24 -0800
From: syzbot <syzbot+28e5f3d207b14bae122a@...kaller.appspotmail.com>
To: davem@...emloft.net, edumazet@...gle.com, eperezma@...hat.com, 
	horms@...nel.org, jasowang@...hat.com, kuba@...nel.org, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, mst@...hat.com, netdev@...r.kernel.org, 
	pabeni@...hat.com, sgarzare@...hat.com, stefanha@...hat.com, 
	syzkaller-bugs@...glegroups.com, virtualization@...ts.linux.dev, 
	xuanzhuo@...ux.alibaba.com
Subject: [syzbot] [kvm?] [net?] [virt?] WARNING in virtio_transport_send_pkt_info
 (2)

Hello,

syzbot found the following issue on:

HEAD commit:    d724c6f85e80 Add linux-next specific files for 20251121
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12920f42580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=763fb984aa266726
dashboard link: https://syzkaller.appspot.com/bug?extid=28e5f3d207b14bae122a
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1458797c580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15afd612580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b2f349c65e3c/disk-d724c6f8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/aba40ae987ce/vmlinux-d724c6f8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0b98fbfe576f/bzImage-d724c6f8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+28e5f3d207b14bae122a@...kaller.appspotmail.com

------------[ cut here ]------------
'send_pkt()' returns 0, but 4096 expected
WARNING: net/vmw_vsock/virtio_transport_common.c:430 at virtio_transport_send_pkt_info+0xd1e/0xef0 net/vmw_vsock/virtio_transport_common.c:428, CPU#1: syz.0.17/5986
Modules linked in:
CPU: 1 UID: 0 PID: 5986 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:virtio_transport_send_pkt_info+0xd1e/0xef0 net/vmw_vsock/virtio_transport_common.c:428
Code: f6 90 0f 0b 90 e9 d7 f7 ff ff e8 5d cc 7c f6 c6 05 c6 5f 64 04 01 90 48 c7 c7 60 da b4 8c 44 89 f6 48 89 ea e8 13 eb 3e f6 90 <0f> 0b 90 90 eb 9e 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c 0a f3 ff ff
RSP: 0018:ffffc900033a7508 EFLAGS: 00010246
RAX: 2383e4149a9d5400 RBX: 0000000000001000 RCX: ffff88807b361e80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: 0000000000001000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffffbfff1c3a720 R12: 0000000000040000
R13: dffffc0000000000 R14: 0000000000000000 R15: ffffc900033a7640
FS:  00005555677a5500(0000) GS:ffff888125b6f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000030000 CR3: 0000000075f06000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 virtio_transport_stream_enqueue net/vmw_vsock/virtio_transport_common.c:1113 [inline]
 virtio_transport_seqpacket_enqueue+0x143/0x1c0 net/vmw_vsock/virtio_transport_common.c:841
 vsock_connectible_sendmsg+0xabf/0x1040 net/vmw_vsock/af_vsock.c:2158
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x21c/0x270 net/socket.c:746
 ____sys_sendmsg+0x52d/0x870 net/socket.c:2634
 ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2688
 __sys_sendmmsg+0x227/0x430 net/socket.c:2777
 __do_sys_sendmmsg net/socket.c:2804 [inline]
 __se_sys_sendmmsg net/socket.c:2801 [inline]
 __x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2801
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1e5218f749
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:00007fffbe398ef8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f1e523e5fa0 RCX: 00007f1e5218f749
RDX: 0000000000000001 RSI: 0000200000000100 RDI: 0000000000000004
RBP: 00007f1e52213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000024008094 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1e523e5fa0 R14: 00007f1e523e5fa0 R15: 0000000000000004
 </TASK>


---
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