packet: validate address length

Packet sockets with SOCK_DGRAM may pass an address for use in
dev_hard_header. Ensure that it is of sufficient length.

Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 0 deletions

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 6655793765b2..5dda263b4a0a 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2627,6 +2627,8 @@ static int tpacket_snd(struct packet_sock *po, struct msghdr *msg)
                 proto   = saddr->sll_protocol;
                 addr    = saddr->sll_addr;
                 dev = dev_get_by_index(sock_net(&po->sk), saddr->sll_ifindex);
+                if (addr && dev && saddr->sll_halen < dev->addr_len)
+                        goto out;
         }
 
         err = -ENXIO;
@@ -2825,6 +2827,8 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
                 proto   = saddr->sll_protocol;
                 addr    = saddr->sll_addr;
                 dev = dev_get_by_index(sock_net(sk), saddr->sll_ifindex);
+                if (addr && dev && saddr->sll_halen < dev->addr_len)
+                        goto out;
         }
 
         err = -ENXIO;