Re: [PATCH] netfilter: h323: bug in parsing of ASN1 SEQOF field

On 23.03.2011 03:33, David Miller wrote:

From: David Sterba <redacted>
Date: Tue, 22 Mar 2011 12:55:29 +0100

quoted

Static analyzer of clang found a dead store which appears to be a bug in
reading count of items in SEQOF field, only the lower byte of word is
stored. This may lead to corrupted read and communication shutdown.

The bug has been in the module since it's first inclusion into linux
kernel.

Signed-off-by: David Sterba <redacted>

Please send netfilter patches to the listed netfilter maintainer
and appropriate mailing lists.  I've added them to the CC:

Otherwise your patch will not be looked at by the right people.

quoted

CC: David Miller <davem@davemloft.net>
CC: netdev@vger.kernel.org
CC: stable@kernel.org
---
 net/netfilter/nf_conntrack_h323_asn1.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/netfilter/nf_conntrack_h323_asn1.c b/net/netfilter/nf_conntrack_h323_asn1.c
index 8678823..bcd5ed6 100644
--- a/net/netfilter/nf_conntrack_h323_asn1.c
+++ b/net/netfilter/nf_conntrack_h323_asn1.c

@@ -631,7 +631,7 @@ static int decode_seqof(bitstr_t *bs, const struct field_t *f,
 		CHECK_BOUND(bs, 2);
 		count = *bs->cur++;
 		count <<= 8;
-		count = *bs->cur++;
+		count += *bs->cur++;
 		break;

This looks correct to me. The problem is without practical consequence
though, the largest amount of sequence-of members we parse is 30.

Applied, thanks.