From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Date: Wed, 6 Aug 2014 23:10:22 +0000 (-0700)
Subject: lib: bitmap: add missing mask in bitmap_and
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=7e5f97d1927f41affa21aa5b321865ceab1994ce;p=deliverable%2Flinux.git

lib: bitmap: add missing mask in bitmap_and

Apparently, bitmap_and is supposed to return whether the new bitmap is
empty.  But it didn't take potential garbage bits in the last word into
account.

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 75df61d9ecfb..3399a9ecd991 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -191,7 +191,7 @@ static inline int bitmap_and(unsigned long *dst, const unsigned long *src1,
 			const unsigned long *src2, unsigned int nbits)
 {
 	if (small_const_nbits(nbits))
-		return (*dst = *src1 & *src2) != 0;
+		return (*dst = *src1 & *src2 & BITMAP_LAST_WORD_MASK(nbits)) != 0;
 	return __bitmap_and(dst, src1, src2, nbits);
 }
 
diff --git a/lib/bitmap.c b/lib/bitmap.c
index faaf7206d4cf..ce2ec80bf431 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -185,11 +185,14 @@ int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
 				const unsigned long *bitmap2, unsigned int bits)
 {
 	unsigned int k;
-	unsigned int nr = BITS_TO_LONGS(bits);
+	unsigned int lim = bits/BITS_PER_LONG;
 	unsigned long result = 0;
 
-	for (k = 0; k < nr; k++)
+	for (k = 0; k < lim; k++)
 		result |= (dst[k] = bitmap1[k] & bitmap2[k]);
+	if (bits % BITS_PER_LONG)
+		result |= (dst[k] = bitmap1[k] & bitmap2[k] &
+			   BITMAP_LAST_WORD_MASK(bits));
 	return result != 0;
 }
 EXPORT_SYMBOL(__bitmap_and);