net/x25: fix address parsing bug in x25_parse_address_block.

From 01ba835311f6d2e2bbffc74703d704dc07803b53 Mon Sep 17 00:00:00 2001
From: Stephen Moorby <[email protected]>
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

---
 net/x25/af_x25.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

index 1d964e2..eb6c1f9 100644
@@ -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