btrfs-progs: convert: Prevent accounting blocks beyond end of device

When looping across data block bitmap, __ext2_add_one_block() may add
blocks which do not exist on the underlying disk. This commit prevents
this from happening by checking the block index against the maximum
block count that was present in the ext4 filesystem instance that is
being converted.

Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Reviewed-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/convert/main.c b/convert/main.c
index 4b4cea4..1148a36 100644 (file)
--- a/convert/main.c
+++ b/convert/main.c
@@ -1525,6 +1525,9 @@ static int __ext2_add_one_block(ext2_filsys fs, char *bitmap,
        offset /= EXT2FS_CLUSTER_RATIO(fs);
        offset += group_nr * EXT2_CLUSTERS_PER_GROUP(fs->super);
        for (i = 0; i < EXT2_CLUSTERS_PER_GROUP(fs->super); i++) {
+               if ((i + offset) >= ext2fs_blocks_count(fs->super))
+                       break;
+
                if (ext2fs_test_bit(i, bitmap)) {
                        u64 start;