netdev - [PATCH net] netfilter: nf_ct_h323: restore boundary check correctness

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Message-Id: <20190403012552.18389-1-shasta@toxcorp.com>
Date:   Wed,  3 Apr 2019 03:25:52 +0200
From:   Jakub Jankowski <shasta@...corp.com>
To:     netdev@...r.kernel.org
Cc:     pablo@...filter.org, fw@...len.de, eric.sesterhenn@...-dsec.de,
        Jakub Jankowski <shasta@...corp.com>
Subject: [PATCH net] netfilter: nf_ct_h323: restore boundary check correctness

Since commit bc7d811ace4a ("netfilter: nf_ct_h323: Convert
CHECK_BOUND macro to function"), NAT traversal for H.323
doesn't work, failing to parse H323-UserInformation.
nf_h323_error_boundary() compares contents of the bitstring,
not the addresses, preventing valid H.323 packets from being
conntrack'd.

This looks like an oversight from when CHECK_BOUND macro was
converted to a function.

To fix it, stop dereferencing bs->cur and bs->end.

Fixes: bc7d811ace4a ("netfilter: nf_ct_h323: Convert CHECK_BOUND macro to function")
Signed-off-by: Jakub Jankowski <shasta@...corp.com>

---
 net/netfilter/nf_conntrack_h323_asn1.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nf_conntrack_h323_asn1.c b/net/netfilter/nf_conntrack_h323_asn1.c
index 1601275efe2d..4c2ef42e189c 100644
--- a/net/netfilter/nf_conntrack_h323_asn1.c
+++ b/net/netfilter/nf_conntrack_h323_asn1.c
@@ -172,7 +172,7 @@ static int nf_h323_error_boundary(struct bitstr *bs, size_t bytes, size_t bits)
 	if (bits % BITS_PER_BYTE > 0)
 		bytes++;
 
-	if (*bs->cur + bytes > *bs->end)
+	if (bs->cur + bytes > bs->end)
 		return 1;
 
 	return 0;
-- 
2.21.0