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, 7 insertions, 4 deletions

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index c34f01513945..7963e03f1068 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -927,18 +927,21 @@ int tcp_v4_md5_do_add(struct sock *sk, __be32 addr,
                         }
                         sk_nocaps_add(sk, NETIF_F_GSO_MASK);
                 }
-                if (tcp_alloc_md5sig_pool(sk) == NULL) {
+
+                md5sig = tp->md5sig_info;
+                if (md5sig->entries4 == 0 &&
+                    tcp_alloc_md5sig_pool(sk) == NULL) {
                         kfree(newkey);
                         return -ENOMEM;
                 }
-                md5sig = tp->md5sig_info;
 
                 if (md5sig->alloced4 == md5sig->entries4) {
                         keys = kmalloc((sizeof(*keys) *
                                         (md5sig->entries4 + 1)), GFP_ATOMIC);
                         if (!keys) {
                                 kfree(newkey);
-                                tcp_free_md5sig_pool();
+                                if (md5sig->entries4 == 0)
+                                        tcp_free_md5sig_pool();
                                 return -ENOMEM;
                         }
 
@@ -982,6 +985,7 @@ int tcp_v4_md5_do_del(struct sock *sk, __be32 addr)
                                 kfree(tp->md5sig_info->keys4);
                                 tp->md5sig_info->keys4 = NULL;
                                 tp->md5sig_info->alloced4 = 0;
+                                tcp_free_md5sig_pool();
                         } else if (tp->md5sig_info->entries4 != i) {
                                 /* Need to do some manipulation */
                                 memmove(&tp->md5sig_info->keys4[i],
@@ -989,7 +993,6 @@ int tcp_v4_md5_do_del(struct sock *sk, __be32 addr)
                                         (tp->md5sig_info->entries4 - i) *
                                          sizeof(struct tcp4_md5sig_key));
                         }
-                        tcp_free_md5sig_pool();
                         return 0;
                 }
         }