[PATCH net] packet: validate address length if non-zero

[Willem de Bruijn]

From: Willem de Bruijn <will...@google.com>

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 <ido...@idosch.org>
Signed-off-by: Willem de Bruijn <will...@google.com>
---
 net/packet/af_packet.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 5dda263b4a0a..eedacdebcd4c 100644
--- 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;
-- 
2.20.1.415.g653613c723-goog