[ 137/147] netfilter: nf_nat_sip: fix incorrect handling of EBUSY for RTCP expectation

Ben Hutchings
2012-10-14T15:13:49Z

From: Pablo Neira Ayuso <pablo@netfilter.org>

commit 3f509c689a07a4aa989b426893d8491a7ffcc410 upstream.

We're hitting bug while trying to reinsert an already existing
expectation:

kernel BUG at kernel/timer.c:895!
invalid opcode: 0000 [#1] SMP
[...]
Call Trace:
<IRQ>
[<ffffffffa0069563>] nf_ct_expect_related_report+0x4a0/0x57a [nf_conntrack]
[<ffffffff812d423a>] ? in4_pton+0x72/0x131
[<ffffffffa00ca69e>] ip_nat_sdp_media+0xeb/0x185 [nf_nat_sip]
[<ffffffffa00b5b9b>] set_expected_rtp_rtcp+0x32d/0x39b [nf_conntrack_sip]
[<ffffffffa00b5f15>] process_sdp+0x30c/0x3ec [nf_conntrack_sip]
[<ffffffff8103f1eb>] ? irq_exit+0x9a/0x9c
[<ffffffffa00ca738>] ? ip_nat_sdp_media+0x185/0x185 [nf_nat_sip]

We have to remove the RTP expectation if the RTCP expectation hits EBUSY
since we keep trying with other ports until we succeed.

Reported-by: Rafal Fitt <rafalf@aplusc.com.pl>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/ipv4/netfilter/nf_nat_sip.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c
index 4ad9cf1..9c87cde 100644
--- a/net/ipv4/netfilter/nf_nat_sip.c
+++ b/net/ipv4/netfilter/nf_nat_sip.c
@@ -502,7 +502,10 @@ static unsigned int ip_nat_sdp_media(struct sk_buff *skb, unsigned int dataoff,
ret = nf_ct_expect_related(rtcp_exp);
if (ret == 0)
break;
- else if (ret != -EBUSY) {
+ else if (ret == -EBUSY) {
+ nf_ct_unexpect_related(rtp_exp);
+ continue;
+ } else if (ret < 0) {
nf_ct_unexpect_related(rtp_exp);
port = 0;
break;