From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Date: Wed, 6 Aug 2014 23:10:20 +0000 (-0700)
Subject: lib: bitmap: add missing mask in bitmap_shift_right
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=c5341ec8904ebff50f365a2626da6ab525d63b9e;p=linux.git

lib: bitmap: add missing mask in bitmap_shift_right

There is no guarantee that *src does not contain garbage bits outside
the lower nbits, so we need to mask it before the shift-and-assign.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 2100378333569..75df61d9ecfb7 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -284,7 +284,7 @@ static inline void bitmap_shift_right(unsigned long *dst,
 			const unsigned long *src, int n, int nbits)
 {
 	if (small_const_nbits(nbits))
-		*dst = *src >> n;
+		*dst = (*src & BITMAP_LAST_WORD_MASK(nbits)) >> n;
 	else
 		__bitmap_shift_right(dst, src, n, nbits);
 }