[50/75] ipv6: ip6_sk_dst_check() must not assume ipv6 dst

Message ID 1375209919-1768-17-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa July 30, 2013, 6:44 p.m. -stable review patch.  If anyone has any objections, please let me know.


From: Eric Dumazet <edumazet@google.com>

[ Upstream commit a963a37d384d71ad43b3e9e79d68d42fbe0901f3 ]

It's possible to use AF_INET6 sockets and to connect to an IPv4
destination. After this, socket dst cache is a pointer to a rtable,
not rt6_info.

ip6_sk_dst_check() should check the socket dst cache is IPv6, or else
various corruptions/crashes can happen.

Dave Jones can reproduce immediate crash with
trinity -q -l off -n -c sendmsg -c connect

With help from Hannes Frederic Sowa

Reported-by: Dave Jones <davej@redhat.com>
Reported-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
 net/ipv6/ip6_output.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)


diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 2adff32..978e4a3 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -843,11 +843,17 @@  static struct dst_entry *ip6_sk_dst_check(struct sock *sk,
 					  const struct flowi6 *fl6)
 	struct ipv6_pinfo *np = inet6_sk(sk);
-	struct rt6_info *rt = (struct rt6_info *)dst;
+	struct rt6_info *rt;
 	if (!dst)
 		goto out;
+	if (dst->ops->family != AF_INET6) {
+		dst_release(dst);
+		return NULL;
+	}
+	rt = (struct rt6_info *)dst;
 	/* Yes, checking route validity in not connected
 	 * case is not very simple. Take into account,
 	 * that we do not support routing by source, TOS,