| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.11 211/329] netfilter: nfnetlink_osf: Fix a missing skb_header_pointer() NULL check | Date | Mon, 17 May 2021 16:02:02 +0200 |
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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 916a3c7f9eaf..79fbf37291f3 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
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