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authorEric Dumazet <eric.dumazet@gmail.com>2009-12-03 01:31:19 +0300
committerDavid S. Miller <davem@davemloft.net>2009-12-04 03:17:43 +0300
commit13475a30b66cdb9250a34052c19ac98847373030 (patch)
tree5f28f671092c2948726fdde92e20c3371cfceb77 /net/ipv6/inet6_hashtables.c
parentff33a6e2ab97f4cde484cdf1a41778af6d6b7cff (diff)
downloadlinux-13475a30b66cdb9250a34052c19ac98847373030.tar.xz
tcp: connect() race with timewait reuse
Its currently possible that several threads issuing a connect() find the same timewait socket and try to reuse it, leading to list corruptions. Condition for bug is that these threads bound their socket on same address/port of to-be-find timewait socket, and connected to same target. (SO_REUSEADDR needed) To fix this problem, we could unhash timewait socket while holding ehash lock, to make sure lookups/changes will be serialized. Only first thread finds the timewait socket, other ones find the established socket and return an EADDRNOTAVAIL error. This second version takes into account Evgeniy's review and makes sure inet_twsk_put() is called outside of locked sections. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6/inet6_hashtables.c')
-rw-r--r--net/ipv6/inet6_hashtables.c15
1 files changed, 10 insertions, 5 deletions
diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 00c6a3e6cddf..c813e294ec0c 100644
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -223,6 +223,7 @@ static int __inet6_check_established(struct inet_timewait_death_row *death_row,
struct sock *sk2;
const struct hlist_nulls_node *node;
struct inet_timewait_sock *tw;
+ int twrefcnt = 0;
spin_lock(lock);
@@ -250,19 +251,23 @@ unique:
* in hash table socket with a funny identity. */
inet->inet_num = lport;
inet->inet_sport = htons(lport);
+ sk->sk_hash = hash;
WARN_ON(!sk_unhashed(sk));
__sk_nulls_add_node_rcu(sk, &head->chain);
- sk->sk_hash = hash;
+ if (tw) {
+ twrefcnt = inet_twsk_unhash(tw);
+ NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
+ }
spin_unlock(lock);
+ if (twrefcnt)
+ inet_twsk_put(tw);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
- if (twp != NULL) {
+ if (twp) {
*twp = tw;
- NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
- } else if (tw != NULL) {
+ } else if (tw) {
/* Silly. Should hash-dance instead... */
inet_twsk_deschedule(tw, death_row);
- NET_INC_STATS_BH(net, LINUX_MIB_TIMEWAITRECYCLED);
inet_twsk_put(tw);
}