From: Behdad Esfahbod <behdad@behdad.org>
Date: Tue, 15 Jan 2019 18:58:19 +0000 (-0500)
Subject: Improve overflow avoidance
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c986ca15a6320d78471adf950394f391e8729b15;p=platform%2Fupstream%2FlibHarfBuzzSharp.git

Improve overflow avoidance

Better fix for 480406cd3ef9e5ab8476ddfa04498bf23906c508
This way we behave the same on 32bit and 64bit archs.
---

diff --git a/src/hb-machinery.hh b/src/hb-machinery.hh
index 07511e1..f1ac848 100644
--- a/src/hb-machinery.hh
+++ b/src/hb-machinery.hh
@@ -268,16 +268,12 @@ struct hb_sanitize_context_t :
     if (!obj) return;
 
     const char *obj_start = (const char *) obj;
-    const char *obj_end = (const char *) obj + obj->get_size ();
-
-    if (unlikely (obj_end < obj_start /* Overflow. */ ||
-		  obj_end < this->start ||
-		  this->end < obj_start))
+    if (unlikely (obj_start < this->start || this->end <= obj_start))
       this->start = this->end = nullptr;
     else
     {
-      this->start = MAX (this->start, obj_start);
-      this->end   = MIN (this->end  , obj_end  );
+      this->start = obj_start;
+      this->end   = obj_start + MIN<uintptr_t> (this->end - obj_start, obj->get_size ());
     }
   }