summaryrefslogtreecommitdiff
path: root/net
diff options
context:
space:
mode:
authorTijs Van Buggenhout <tijs.van.buggenhout@axsguard.com>2023-05-25 13:25:26 +0300
committerPablo Neira Ayuso <pablo@netfilter.org>2023-06-07 01:43:43 +0300
commite1f543dc660b44618a1bd72ddb4ca0828a95f7ad (patch)
treeb4ff9c1aea500f3e0928b99d0d0cdbe3412241ae /net
parent14e8b293903785590a0ef168745ac84250cb1f4c (diff)
downloadlinux-e1f543dc660b44618a1bd72ddb4ca0828a95f7ad.tar.xz
netfilter: conntrack: fix NULL pointer dereference in nf_confirm_cthelper
An nf_conntrack_helper from nf_conn_help may become NULL after DNAT. Observed when TCP port 1720 (Q931_PORT), associated with h323 conntrack helper, is DNAT'ed to another destination port (e.g. 1730), while nfqueue is being used for final acceptance (e.g. snort). This happenned after transition from kernel 4.14 to 5.10.161. Workarounds: * keep the same port (1720) in DNAT * disable nfqueue * disable/unload h323 NAT helper $ linux-5.10/scripts/decode_stacktrace.sh vmlinux < /tmp/kernel.log BUG: kernel NULL pointer dereference, address: 0000000000000084 [..] RIP: 0010:nf_conntrack_update (net/netfilter/nf_conntrack_core.c:2080 net/netfilter/nf_conntrack_core.c:2134) nf_conntrack [..] nfqnl_reinject (net/netfilter/nfnetlink_queue.c:237) nfnetlink_queue nfqnl_recv_verdict (net/netfilter/nfnetlink_queue.c:1230) nfnetlink_queue nfnetlink_rcv_msg (net/netfilter/nfnetlink.c:241) nfnetlink [..] Fixes: ee04805ff54a ("netfilter: conntrack: make conntrack userspace helpers work again") Signed-off-by: Tijs Van Buggenhout <tijs.van.buggenhout@axsguard.com> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/nf_conntrack_core.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index c4ccfec6cb98..d119f1d4c2fc 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -2260,6 +2260,9 @@ static int nf_confirm_cthelper(struct sk_buff *skb, struct nf_conn *ct,
return 0;
helper = rcu_dereference(help->helper);
+ if (!helper)
+ return 0;
+
if (!(helper->flags & NF_CT_HELPER_F_USERSPACE))
return 0;