econet: Fix crash in aun_incoming().

[ Upstream commit 4e085e76cbe558b79b54cbab772f61185879bc64 ]

Unconditional use of skb->dev won't work here,
try to fetch the econet device via skb_dst()->dev
instead.

Suggested by Eric Dumazet.

Reported-by: Nelson Elhage <nelhage@ksplice.com>
Tested-by: Nelson Elhage <nelhage@ksplice.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/econet/af_econet.c b/net/econet/af_econet.c
index 10d404132c496f8c60654c152c32f44aeb584117..172a6a91a2144f413d6b2c5a4540b537c28fce18 100644 (file)
--- a/net/econet/af_econet.c
+++ b/net/econet/af_econet.c
@@ -851,9 +851,13 @@ static void aun_incoming(struct sk_buff *skb, struct aunhdr *ah, size_t len)
 {
        struct iphdr *ip = ip_hdr(skb);
        unsigned char stn = ntohl(ip->saddr) & 0xff;
+       struct dst_entry *dst = skb_dst(skb);
+       struct ec_device *edev = NULL;
        struct sock *sk = NULL;
        struct sk_buff *newskb;
-       struct ec_device *edev = skb->dev->ec_ptr;
+
+       if (dst)
+               edev = dst->dev->ec_ptr;
 
        if (! edev)
                goto bad;