netdev - [PATCH net] packet: validate address length

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Message-Id: <20181221170659.93678-1-willemdebruijn.kernel@gmail.com>
Date:   Fri, 21 Dec 2018 12:06:59 -0500
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     netdev@...r.kernel.org
Cc:     edumazet@...gle.com, Willem de Bruijn <willemb@...gle.com>,
        syzbot <syzkaller@...glegroups.com>
Subject: [PATCH net] packet: validate address length

From: Willem de Bruijn <willemb@...gle.com>

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@...glegroups.com>
Signed-off-by: Willem de Bruijn <willemb@...gle.com>
---
 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 6655793765b2d..5dda263b4a0a1 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;
-- 
2.20.1.415.g653613c723-goog