libext2fs: fix 64bit overflow in ext2fs_block_alloc_stats_range

In ext2fs_block_alloc_stats_range(), the quantity "-inuse * n" is
calculated as a signed 32-bit quantity.  Unfortunately, gcc (4.6.3 on
Ubuntu 12.04) doesn't sign-extend this quantity to fill the blk64_t
parameter that ext2fs_free_blocks_count_add() wants, so the end result
is that the superblock gets a ridiculously huge free block count.

Changing the declaration of 'n' to blk64_t seems to fix this.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/lib/ext2fs/alloc_stats.c b/lib/ext2fs/alloc_stats.c
index 5bb86ef..4feb24d 100644 (file)
--- a/lib/ext2fs/alloc_stats.c
+++ b/lib/ext2fs/alloc_stats.c
@@ -129,7 +129,7 @@ void ext2fs_block_alloc_stats_range(ext2_filsys fs, blk64_t blk,
        while (num) {
                int group = ext2fs_group_of_blk2(fs, blk);
                blk64_t last_blk = ext2fs_group_last_block2(fs, group);
-               blk_t n = num;
+               blk64_t n = num;
 
                if (blk + num > last_blk)
                        n = last_blk - blk + 1;