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authorPablo Neira Ayuso <pablo@netfilter.org>2021-05-05 22:25:24 +0200
committerPablo Neira Ayuso <pablo@netfilter.org>2021-05-05 22:26:09 +0200
commit5e024c325406470d1165a09c6feaf8ec897936be (patch)
treef0c342e641912b5e6e41e0965971f1410bc2a44c /net
parent7072a355ba191c08b0579f0f66e3eba0e28bf818 (diff)
netfilter: nfnetlink_osf: Fix a missing skb_header_pointer() NULL check
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>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/nfnetlink_osf.c2
1 files changed, 2 insertions, 0 deletions
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;