sctp: fix dst refcnt leak in sctp_v6_get_dst()

BugLink: http://bugs.launchpad.net/bugs/1755179
[ Upstream commit 957d761cf91cdbb175ad7d8f5472336a4d54dbf2 ]

When going through the bind address list in sctp_v6_get_dst() and
the previously found address is better ('matchlen > bmatchlen'),
the code continues to the next iteration without releasing currently
held destination.

Fix it by releasing 'bdst' before continue to the next iteration, and
instead of introducing one more '!IS_ERR(bdst)' check for dst_release(),
move the already existed one right after ip6_dst_lookup_flow(), i.e. we
shouldn't proceed further if we get an error for the route lookup.

Fixes: dbc2b5e9a09e ("sctp: fix src address selection if using secondary addresses for ipv6")
Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index 5d4c15bf66d26219415596598a1f72d29b63a798..e35d4f73d2dffffea6d966714ce7f011b3fdeae5 100644 (file)
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -326,8 +326,10 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
                final_p = fl6_update_dst(fl6, rcu_dereference(np->opt), &final);
                bdst = ip6_dst_lookup_flow(sk, fl6, final_p);
 
-               if (!IS_ERR(bdst) &&
-                   ipv6_chk_addr(dev_net(bdst->dev),
+               if (IS_ERR(bdst))
+                       continue;
+
+               if (ipv6_chk_addr(dev_net(bdst->dev),
                                  &laddr->a.v6.sin6_addr, bdst->dev, 1)) {
                        if (!IS_ERR_OR_NULL(dst))
                                dst_release(dst);
@@ -336,8 +338,10 @@ static void sctp_v6_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
                }
 
                bmatchlen = sctp_v6_addr_match_len(daddr, &laddr->a);
-               if (matchlen > bmatchlen)
+               if (matchlen > bmatchlen) {
+                       dst_release(bdst);
                        continue;
+               }
 
                if (!IS_ERR_OR_NULL(dst))
                        dst_release(dst);