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authorEric Dumazet <eric.dumazet@gmail.com>2009-12-02 22:31:19 +0000
committerDavid S. Miller <davem@davemloft.net>2009-12-03 16:17:43 -0800
commit13475a30b66cdb9250a34052c19ac98847373030 (patch)
tree5f28f671092c2948726fdde92e20c3371cfceb77 /net/ipv4/inet_timewait_sock.c
parentbe2net: Add support for ethtool self test (diff)
downloadlinux-dev-13475a30b66cdb9250a34052c19ac98847373030.tar.xz
linux-dev-13475a30b66cdb9250a34052c19ac98847373030.zip
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/ipv4/inet_timewait_sock.c')
-rw-r--r--net/ipv4/inet_timewait_sock.c38
1 files changed, 28 insertions, 10 deletions
diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 31f931ef3daf..11a107a5af4f 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -14,22 +14,33 @@
#include <net/inet_timewait_sock.h>
#include <net/ip.h>
+
+/*
+ * unhash a timewait socket from established hash
+ * lock must be hold by caller
+ */
+int inet_twsk_unhash(struct inet_timewait_sock *tw)
+{
+ if (hlist_nulls_unhashed(&tw->tw_node))
+ return 0;
+
+ hlist_nulls_del_rcu(&tw->tw_node);
+ sk_nulls_node_init(&tw->tw_node);
+ return 1;
+}
+
/* Must be called with locally disabled BHs. */
static void __inet_twsk_kill(struct inet_timewait_sock *tw,
struct inet_hashinfo *hashinfo)
{
struct inet_bind_hashbucket *bhead;
struct inet_bind_bucket *tb;
+ int refcnt;
/* Unlink from established hashes. */
spinlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash);
spin_lock(lock);
- if (hlist_nulls_unhashed(&tw->tw_node)) {
- spin_unlock(lock);
- return;
- }
- hlist_nulls_del_rcu(&tw->tw_node);
- sk_nulls_node_init(&tw->tw_node);
+ refcnt = inet_twsk_unhash(tw);
spin_unlock(lock);
/* Disassociate with bind bucket. */
@@ -37,9 +48,12 @@ static void __inet_twsk_kill(struct inet_timewait_sock *tw,
hashinfo->bhash_size)];
spin_lock(&bhead->lock);
tb = tw->tw_tb;
- __hlist_del(&tw->tw_bind_node);
- tw->tw_tb = NULL;
- inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
+ if (tb) {
+ __hlist_del(&tw->tw_bind_node);
+ tw->tw_tb = NULL;
+ inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb);
+ refcnt++;
+ }
spin_unlock(&bhead->lock);
#ifdef SOCK_REFCNT_DEBUG
if (atomic_read(&tw->tw_refcnt) != 1) {
@@ -47,7 +61,10 @@ static void __inet_twsk_kill(struct inet_timewait_sock *tw,
tw->tw_prot->name, tw, atomic_read(&tw->tw_refcnt));
}
#endif
- inet_twsk_put(tw);
+ while (refcnt) {
+ inet_twsk_put(tw);
+ refcnt--;
+ }
}
static noinline void inet_twsk_free(struct inet_timewait_sock *tw)
@@ -92,6 +109,7 @@ void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
tw->tw_tb = icsk->icsk_bind_hash;
WARN_ON(!icsk->icsk_bind_hash);
inet_twsk_add_bind_node(tw, &tw->tw_tb->owners);
+ atomic_inc(&tw->tw_refcnt);
spin_unlock(&bhead->lock);
spin_lock(lock);