[PATCH net] af_packet: Don't send zero-byte data in tpacket_snd().
Eric Dumazet <[email protected]>
| Newsgroups | org.kernel.vger.netdev |
|---|---|
| Message-ID | <[email protected]> |
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().
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: [email protected]
Closes: https://lore.kernel.org/netdev/[email protected]/T/#u
Signed-off-by: Eric Dumazet <[email protected]>
---
net/packet/af_packet.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 435756877abaa1ab4c0edcc2346bcb2de3625605..103025c4625fb317e0ecedd12c15857af86b7a65 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2660,6 +2660,9 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
len = ((to_write > len_max) ? len_max : to_write);
}
+ if (unlikely(!skb->len))
+ return -EINVAL;
+
packet_parse_headers(skb, sock);
return tp_len;
--
2.55.0.654.g21b8a5bc05-goog