From 6b69fe0c73c0f5a8dacf8f889db3cc9adee53649 Mon Sep 17 00:00:00 2001 From: Patrick McHardy Date: Wed, 9 Jul 2008 15:06:12 -0700 Subject: netfilter: nf_conntrack_tcp: fix endless loop When a conntrack entry is destroyed in process context and destruction is interrupted by packet processing and the packet is an attempt to reopen a closed connection, TCP conntrack tries to kill the old entry itself and returns NF_REPEAT to pass the packet through the hook again. This may lead to an endless loop: TCP conntrack repeatedly finds the old entry, but can not kill it itself since destruction is already in progress, but destruction in process context can not complete since TCP conntrack is keeping the CPU busy. Drop the packet in TCP conntrack if we can't kill the connection ourselves to avoid this. Reported by: hemao77@gmail.com [ Kernel bugzilla #11058 ] Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- net/netfilter/nf_conntrack_proto_tcp.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'net') diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c index 271cd01d57ae..dd28fb239a60 100644 --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -844,9 +844,15 @@ static int tcp_packet(struct nf_conn *ct, /* Attempt to reopen a closed/aborted connection. * Delete this connection and look up again. */ write_unlock_bh(&tcp_lock); - if (del_timer(&ct->timeout)) + /* Only repeat if we can actually remove the timer. + * Destruction may already be in progress in process + * context and we must give it a chance to terminate. + */ + if (del_timer(&ct->timeout)) { ct->timeout.function((unsigned long)ct); - return -NF_REPEAT; + return -NF_REPEAT; + } + return -NF_DROP; } /* Fall through */ case TCP_CONNTRACK_IGNORE: -- cgit v1.2.3