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authorEric Dumazet <edumazet@google.com>2015-08-13 15:44:51 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-10-22 14:43:24 -0700
commitd3a1196bfc462943694623412d8e03aaf172bdc1 (patch)
treea737edd76bf1ee1a78ff440b6620017680235f5e
parenta58897f9e663bb9b64b703f7dd451c7089cb28bb (diff)
inet: fix potential deadlock in reqsk_queue_unlink()
commit 83fccfc3940c4a2db90fd7e7079f5b465cd8c6af upstream. When replacing del_timer() with del_timer_sync(), I introduced a deadlock condition : reqsk_queue_unlink() is called from inet_csk_reqsk_queue_drop() inet_csk_reqsk_queue_drop() can be called from many contexts, one being the timer handler itself (reqsk_timer_handler()). In this case, del_timer_sync() loops forever. Simple fix is to test if timer is pending. Fixes: 2235f2ac75fd ("inet: fix races with reqsk timers") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Cc: Holger Hoffstätte <holger.hoffstaette@googlemail.com> Cc: Andre Tomt <andre@tomt.net> Cc: Chris Caputo <ccaputo@alt.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--net/ipv4/inet_connection_sock.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index b27fc401c6a9..e664706b350c 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -584,7 +584,7 @@ static bool reqsk_queue_unlink(struct request_sock_queue *queue,
}
spin_unlock(&queue->syn_wait_lock);
- if (del_timer_sync(&req->rsk_timer))
+ if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
reqsk_put(req);
return found;
}