commit a8f380e9330ffa6d08b172041433ed46adc7b207
Author: Andrew Price <anprice@redhat.com>
Date:   Mon Aug 19 15:23:57 2013 +0100

    fsck.gfs2: Allocate enough space for the block map
    
    Building with gcc 4.8's address sanitizer and running the test suite
    throws up an issue where the block map allocated in fsck.gfs2 is not
    large enough when the required size is an odd number. For example, when
    the number of blocks is 3, the mapsize (number of chars to allocate
    memory for) would be (3 >> 1) which is too small as each block requires
    4 bits. This patch adds 1 to the mapsize, as suggested in an existing
    comment, to ensure we have enough space in these situations.
    
    Note that this has (probably) never made fsck.gfs2 misbehave as it only
    ever accessed 4 bits past the end of the block map and by chance that
    memory was never being modified by anything else in the rare cases in
    which it was used.
    
    Resolves: bz#1001583
    
    Signed-off-by: Andrew Price <anprice@redhat.com>

diff --git a/gfs2/fsck/util.c b/gfs2/fsck/util.c
index 408d89a..3e3050f 100644
--- a/gfs2/fsck/util.c
+++ b/gfs2/fsck/util.c
@@ -534,15 +534,10 @@ static int gfs2_blockmap_create(struct gfs2_bmap *bmap, uint64_t size)
 
 	/* Have to add 1 to BLOCKMAP_SIZE since it's 0-based and mallocs
 	 * must be 1-based */
-	bmap->mapsize = BLOCKMAP_SIZE4(size);
+	bmap->mapsize = BLOCKMAP_SIZE4(size) + 1;
 
-	if (!(bmap->map = malloc(sizeof(char) * bmap->mapsize)))
+	if (!(bmap->map = calloc(bmap->mapsize, sizeof(char))))
 		return -ENOMEM;
-	if (!memset(bmap->map, 0, sizeof(char) * bmap->mapsize)) {
-		free(bmap->map);
-		bmap->map = NULL;
-		return -ENOMEM;
-	}
 	return 0;
 }