Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

[linux-2.6-microblaze.git] / net / ipv4 / tcp_ipv4.c

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index ea0df9f..116c11a 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1111,9 +1111,21 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
 
        key = tcp_md5_do_lookup_exact(sk, addr, family, prefixlen, l3index);
        if (key) {
-               /* Pre-existing entry - just update that one. */
-               memcpy(key->key, newkey, newkeylen);
-               key->keylen = newkeylen;
+               /* Pre-existing entry - just update that one.
+                * Note that the key might be used concurrently.
+                * data_race() is telling kcsan that we do not care of
+                * key mismatches, since changing MD5 key on live flows
+                * can lead to packet drops.
+                */
+               data_race(memcpy(key->key, newkey, newkeylen));
+
+               /* Pairs with READ_ONCE() in tcp_md5_hash_key().
+                * Also note that a reader could catch new key->keylen value
+                * but old key->key[], this is the reason we use __GFP_ZERO
+                * at sock_kmalloc() time below these lines.
+                */
+               WRITE_ONCE(key->keylen, newkeylen);
+
                return 0;
        }
 
@@ -1129,7 +1141,7 @@ int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
                rcu_assign_pointer(tp->md5sig_info, md5sig);
        }
 
-       key = sock_kmalloc(sk, sizeof(*key), gfp);
+       key = sock_kmalloc(sk, sizeof(*key), gfp | __GFP_ZERO);
        if (!key)
                return -ENOMEM;
        if (!tcp_alloc_md5sig_pool()) {