From b7737eacf173f52fd99e073f8f60c92216b32246 Mon Sep 17 00:00:00 2001
From: Thomas Faber <thomas.faber@reactos.org>
Date: Mon, 31 Mar 2014 19:57:42 +0000
Subject: [PATCH] [RTL] - Fix buffer overrun in RtlNumberOfSetBits

svn path=/trunk/; revision=62591
---
 reactos/lib/rtl/bitmap.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/reactos/lib/rtl/bitmap.c b/reactos/lib/rtl/bitmap.c
index b009355dc90..6ceddf927ee 100644
--- a/reactos/lib/rtl/bitmap.c
+++ b/reactos/lib/rtl/bitmap.c
@@ -467,8 +467,11 @@ RtlNumberOfSetBits(
         BitCount += BitCountTable[*Byte++];
     }
 
-    Shift = 8 - (BitMapHeader->SizeOfBitMap & 7);
-    BitCount += BitCountTable[((*Byte) << Shift) & 0xFF];
+    if (BitMapHeader->SizeOfBitMap & 7)
+    {
+        Shift = 8 - (BitMapHeader->SizeOfBitMap & 7);
+        BitCount += BitCountTable[((*Byte) << Shift) & 0xFF];
+    }
 
     return BitCount;
 }