From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Fri, 15 Jan 2016 15:02:00 +0000 (+0000)
Subject: Avoid overflow in compare_extable_entry() when entries are far appart
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=d49a4a797514c019c7015f191c5f49e522d7a999;p=people%2Froyger%2Fxen-test-framework.git

Avoid overflow in compare_extable_entry() when entries are far appart

Constrain the return value to strictly between -1 and 1.  Without this,
sorting extable entries which are further than 2GB apart fails, as the
calculation overflows the return value.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---

diff --git a/common/extable.c b/common/extable.c
index d5b47c9..b28dd78 100644
--- a/common/extable.c
+++ b/common/extable.c
@@ -33,7 +33,12 @@ static int compare_extable_entry(const void *_l, const void *_r)
 {
     const struct extable_entry *l = _l, *r = _r;
 
-    return l->fault - r->fault;
+    if ( l->fault == r->fault )
+        return 0;
+    else if ( l->fault > r->fault )
+        return 1;
+    else
+        return -1;
 }
 
 static void swap_extable_entry(void *_l, void *_r)