Eric Dumazet 6bcd76c134 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 dc633700f0 ("net/af_packet: check len when min_header_len equals to 0") and in packet_sendmsg_spkt() via commit 6a341729fb ("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(). Fixes: 1da177e4c3 ("Linux-2.6.12-rc2") Reported-by: syzbot+30b93b6845b19cc38581@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/6a79e807.01d0871a.3a0d52.00ac.GAE@google.com/T/#u Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Willem de Bruijn <willemb@google.com> Reviewed-by: Jiayuan Chen <jiayuan.chen@linux.dev> Link: https://patch.msgid.link/20260810150447.1220864-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>		2026-08-11 17:32:53 -07:00
..
af_packet.c	af_packet: Don't send zero-byte data in tpacket_snd().	2026-08-11 17:32:53 -07:00
diag.c	net: change sock.sk_ino and sock_i_ino() to u64	2026-03-06 14:31:26 +01:00
internal.h	net: af_packet: Use hrtimer to do the retire operation	2025-09-11 18:40:06 -07:00
Kconfig	treewide: replace '---help---' in Kconfig files with 'help'	2020-06-14 01:57:21 +09:00
Makefile	treewide: Add SPDX license identifier - Makefile/Kconfig	2019-05-21 10:50:46 +02:00