From: Pablo Neira Ayuso pablo@netfilter.org
[ Upstream commit 5e024c325406470d1165a09c6feaf8ec897936be ]
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@netfilter.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 131f9f8c0b09..917f06110c82 100644 --- a/net/netfilter/nfnetlink_osf.c +++ b/net/netfilter/nfnetlink_osf.c @@ -191,6 +191,8 @@ 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;