diff mbox series

[4.19,357/425] netfilter: nfnetlink_osf: Fix a missing skb_header_pointer() NULL check

Message ID 20210520092143.142249257@linuxfoundation.org
State New
Headers show
Series None | expand

Commit Message

Greg KH May 20, 2021, 9:22 a.m. UTC 
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 mbox series

Patch

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;