linux-kernel - [PATCH 1/1] net/x25: fix address parsing bug in x25_parse_address

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Date:	Wed, 19 Jun 2013 21:32:36 +0100
From:	Stephen Moorby <steve.moorby@...world.com>
To:	davem@...emloft.net, sasha.levin@...cle.com,
	akpm@...ux-foundation.org, paulmck@...ux.vnet.ibm.com,
	jiri@...nulli.us, linux-x25@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	Stephen Moorby <steve.moorby@...world.com>
Subject: [PATCH 1/1] net/x25: fix address parsing bug in x25_parse_address_block.

This problem was discovered when a linux box was incorrectly rejecting
calls from some X.25 equipment.  The problem was diagnosed to an incorrect
address length calculation in 'x25_parse_address_block', the calculation
did not account for the address digits being BCD encoded.  The correct
calculation is already performed on line 155.

Patched on linux-next 18-Jun-2013
Tested on 2.6.32-45-generic

Signed-off-by: Stephen Moorby <steve.moorby@...world.com>
---
 net/x25/af_x25.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/x25/af_x25.c b/net/x25/af_x25.c
index 1d964e2..eb6c1f9 100644
--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -98,7 +98,8 @@ int x25_parse_address_block(struct sk_buff *skb,
 	}
 
 	len = *skb->data;
-	needed = 1 + (len >> 4) + (len & 0x0f);
+	/* need 1 for address length + bytes for BCD encoding of 2 addresses */
+	needed = 1 + (((len >> 4) + (len & 0x0f) + 1) >> 1);
 
 	if (!pskb_may_pull(skb, needed)) {
 		/* packet is too short to hold the addresses it claims
-- 
1.8.1.2

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