packet: validate address length if non-zero

Validate packet socket address length if a length is given. Zero
length is equivalent to not setting an address.

Fixes: 99137b7888f4 ("packet: validate address length")
Reported-by: Ido Schimmel <idosch@idosch.org>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 5dda263b4a0a12e05c90329bfda18fc24a0c1de7..eedacdebcd4c61c7fbd3f781b993fee7ce00500f 100644 (file)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2625,7 +2625,7 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
                                                sll_addr)))
                        goto out;
                proto   = saddr->sll_protocol;
-               addr    = saddr->sll_addr;
+               addr    = saddr->sll_halen ? saddr->sll_addr : NULL;
                dev = dev_get_by_index(sock_net(&po->sk), saddr->sll_ifindex);
                if (addr && dev && saddr->sll_halen < dev->addr_len)
                        goto out;
@@ -2825,7 +2825,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
                if (msg->msg_namelen < (saddr->sll_halen + offsetof(struct sockaddr_ll, sll_addr)))
                        goto out;
                proto   = saddr->sll_protocol;
-               addr    = saddr->sll_addr;
+               addr    = saddr->sll_halen ? saddr->sll_addr : NULL;
                dev = dev_get_by_index(sock_net(sk), saddr->sll_ifindex);
                if (addr && dev && saddr->sll_halen < dev->addr_len)
                        goto out;