sctp: fix dst refcnt leak in sctp_v6_get_dst()

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>

1 files changed, 7 insertions, 3 deletions

diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index 5d4c15bf66d2..e35d4f73d2df 100644
--- 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);