CVE-2026-80742

In the Linux kernel, the following vulnerability has been resolved:

af_packet: Don't send zero-byte data in tpacket_snd().

syzbot reported a WARNING in __dev_queue_xmit() triggered via tpacket_snd():

skb_assert_len

WARNING: at include/linux/skbuff.h:2753 skb_assert_len

WARNING: at __dev_queue_xmit+0x21bc/0x4970 net/core/dev.c:4781

Call Trace:

<TASK>

dev_queue_xmit include/linux/netdevice.h:3448 [inline]

packet_xmit+0x243/0x310 net/packet/af_packet.c:276

tpacket_snd net/packet/af_packet.c:2907 [inline]

packet_sendmsg+0x28d6/0x4eb0 net/packet/af_packet.c:3134

When sending 0-byte packets via TPACKET ring buffer on devices with no

hard header (e.g. dev->hard_header_len == 0), tpacket_fill_skb()

populates an skb with skb->len == 0 and returns 0. tpacket_snd() then

forwards this empty skb to packet_xmit(), causing __dev_queue_xmit() to

hit skb_assert_len(skb).

Similar checks exist in packet_snd() via commit dc633700f00f

("net/af_packet: check len when min_header_len equals to 0") and in

packet_sendmsg_spkt() via commit 6a341729fb31 ("af_packet: Don't send

zero-byte data in packet_sendmsg_spkt().").

Return -EINVAL in tpacket_fill_skb() when skb->len is zero to reject

zero-length packets in tpacket_snd().