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

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Message-ID: <51C19258.9070504@keyparts.co.uk>
Date:	Wed, 19 Jun 2013 12:13:28 +0100
From:	Stephen Moorby <steve@...parts.co.uk>
To:	andrew.hendry@...il.com, 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
Subject: [PATCH 1/1] net/x25: fix address parsing bug in x25_parse_address_block.

 From 01ba835311f6d2e2bbffc74703d704dc07803b53 Mon Sep 17 00:00:00 2001
From: Stephen Moorby <steve.moorby@...world.com>
Date: Wed, 19 Jun 2013 11:48:53 +0100
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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