tcp: properly handle md5sig_pool references

tcp_v4_clear_md5_list() assumes that multiple tcp md5sig peers
only hold one reference to md5sig_pool. but tcp_v4_md5_do_add()
increases use count of md5sig_pool for each peer. This patch
makes tcp_v4_md5_do_add() only increases use count for the first
tcp md5sig peer.

Signed-off-by: Zheng Yan <zheng.z.yan@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 3 deletions

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 79cc6469508d..7b8fc5794352 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -591,7 +591,8 @@ static int tcp_v6_md5_do_add(struct sock *sk, const struct in6_addr *peer,
                         }
                         sk_nocaps_add(sk, NETIF_F_GSO_MASK);
                 }
-                if (tcp_alloc_md5sig_pool(sk) == NULL) {
+                if (tp->md5sig_info->entries6 == 0 &&
+                        tcp_alloc_md5sig_pool(sk) == NULL) {
                         kfree(newkey);
                         return -ENOMEM;
                 }
@@ -600,8 +601,9 @@ static int tcp_v6_md5_do_add(struct sock *sk, const struct in6_addr *peer,
                                        (tp->md5sig_info->entries6 + 1)), GFP_ATOMIC);
 
                         if (!keys) {
-                                tcp_free_md5sig_pool();
                                 kfree(newkey);
+                                if (tp->md5sig_info->entries6 == 0)
+                                        tcp_free_md5sig_pool();
                                 return -ENOMEM;
                         }
 
@@ -647,6 +649,7 @@ static int tcp_v6_md5_do_del(struct sock *sk, const struct in6_addr *peer)
                                 kfree(tp->md5sig_info->keys6);
                                 tp->md5sig_info->keys6 = NULL;
                                 tp->md5sig_info->alloced6 = 0;
+                                tcp_free_md5sig_pool();
                         } else {
                                 /* shrink the database */
                                 if (tp->md5sig_info->entries6 != i)
@@ -655,7 +658,6 @@ static int tcp_v6_md5_do_del(struct sock *sk, const struct in6_addr *peer)
                                                 (tp->md5sig_info->entries6 - i)
                                                 * sizeof (tp->md5sig_info->keys6[0]));
                         }
-                        tcp_free_md5sig_pool();
                         return 0;
                 }
         }