From: Gao Feng <f...@ikuai8.com>
The current call path of nf_ct_tcp_seqadj_set is the following.
nfqnl_recv_verdict->ctnetlink_glue_hook->ctnetlink_glue_seqadj
->nf_ct_tcp_seqadj_set.
It couldn't make sure the TCP header is in the linear data part.
So use the skb_header_pointer instead of the current codes.
BTW, the nf_ct_tcp_seqadj_set is one external function of netfilter
which works in the network layer, it should not assume the transport
header is in the linear data.
Signed-off-by: Gao Feng <f...@ikuai8.com>
---
net/netfilter/nf_conntrack_seqadj.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/net/netfilter/nf_conntrack_seqadj.c
b/net/netfilter/nf_conntrack_seqadj.c
index ef7063e..80394ab 100644
--- a/net/netfilter/nf_conntrack_seqadj.c
+++ b/net/netfilter/nf_conntrack_seqadj.c
@@ -61,11 +61,14 @@ void nf_ct_tcp_seqadj_set(struct sk_buff *skb,
s32 off)
{
const struct tcphdr *th;
+ struct tcphdr tcph;
if (nf_ct_protonum(ct) != IPPROTO_TCP)
return;
- th = (struct tcphdr *)(skb_network_header(skb) + ip_hdrlen(skb));
+ th = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(tcph), &tcph);
+ if (!th)
+ return;
nf_ct_seqadj_set(ct, ctinfo, th->seq, off);
}
EXPORT_SYMBOL_GPL(nf_ct_tcp_seqadj_set);
--
1.9.1
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