Do not assume that the tcph->doff field is correct when parsing for TCP
options, skb_header_pointer() might fail to fetch these bits.
Fixes: 11eeef41d5f6 ("netfilter: passive OS fingerprint xtables match")
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
net/netfilter/nfnetlink_osf.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/netfilter/nfnetlink_osf.c b/net/netfilter/nfnetlink_osf.c
index e8f8875c6884..0fa2e2030427 100644
--- a/net/netfilter/nfnetlink_osf.c
+++ b/net/netfilter/nfnetlink_osf.c
@@ -186,6 +186,8 @@ static const struct tcphdr *nf_osf_hdr_ctx_init(struct nf_osf_hdr_ctx *ctx,
ctx->optp = skb_header_pointer(skb, ip_hdrlen(skb) +
sizeof(struct tcphdr), ctx->optsize, opts);
+ if (!ctx->optp)
+ return NULL;
}
return tcp;
--
2.30.2
