From 657ee2da596a783b6df1c5d056bf982435ed39e8 Mon Sep 17 00:00:00 2001
From: Sven Hesse
Date: Thu, 20 Oct 2011 20:47:53 +0200
Subject: COMMON: Fix potential UB while shifting Common::BitStream

Shifting a 32-bit value by more than 31 is undefined.
---
 common/bitstream.h | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'common')

diff --git a/common/bitstream.h b/common/bitstream.h
index 34063dbfe1..61ec4abc76 100644
--- a/common/bitstream.h
+++ b/common/bitstream.h
@@ -176,6 +176,9 @@ public:
 
 	/** Read a multi-bit value from the bit stream. */
 	uint32 getBits(uint8 n) {
+		if (n == 0)
+			return 0;
+
 		if (n > 32)
 			error("BitStreamImpl::getBits(): Too many bits requested to be read");
 
@@ -225,6 +228,9 @@ public:
 
 	/** Add a bit to the value x, making it an n-bit value. */
 	void addBit(uint32 &x, uint32 n) {
+		if (n >= 32)
+			error("BitStreamImpl::addBit(): Too many bits requested to be read");
+
 		if (isMSB2LSB)
 			x = (x << 1) | getBit();
 		else
-- 
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