From: Willem de Bruijn <willemb@google.com>
Date: Fri, 21 Dec 2018 12:06:59 -0500
Subject: packet: validate address length
Git-commit: 99137b7888f4058087895d035d81c6b2d31015c5
Patch-mainline: v4.20
References: networking-stable-19_01_04

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>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/packet/af_packet.c | 4 ++++
 1 file changed, 4 insertions(+)

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;
-- 
2.20.1