net/af_packet: check len when min_header_len equals to 0

commit dc633700f00f726e027846a318c5ffeb8deaaeda upstream.

User can use AF_PACKET socket to send packets with the length of 0.
When min_header_len equals to 0, packet_snd will call __dev_queue_xmit
to send packets, and sock->type can be any type.

Reported-by: syzbot+5ea725c25d06fb9114c4@syzkaller.appspotmail.com
Fixes: fd1894224407 ("bpf: Don't redirect packets with invalid pkt_len")
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 88c3b5c..968dac3 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2989,8 +2989,8 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
        if (err)
                goto out_free;
 
-       if (sock->type == SOCK_RAW &&
-           !dev_validate_header(dev, skb->data, len)) {
+       if ((sock->type == SOCK_RAW &&
+            !dev_validate_header(dev, skb->data, len)) || !skb->len) {
                err = -EINVAL;
                goto out_free;
        }