ipv4: make ip_append_data() handle NULL routing table

Add a check in ip_append_data() for NULL *rtp to prevent future bugs in
callers from being exploitable.

Signed-off-by: Julien Tinnes <julien@cr0.org>
Signed-off-by: Tavis Ormandy <taviso@sdf.lonestar.org>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 7d0821054729..7ffcd96fe591 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -813,6 +813,8 @@ int ip_append_data(struct sock *sk,
                         inet->cork.addr = ipc->addr;
                 }
                 rt = *rtp;
+                if (unlikely(!rt))
+                        return -EFAULT;
                 /*
                  * We steal reference to this route, caller should not release it
                  */