From: Jan Kara jack@suse.cz
commit 31562b954b60f02acb91b7349dc6432d3f8c3c5f upstream.
The sanity check in mb_find_extent() only checked that returned extent does not extend past blocksize * 8, however it should not extend past EXT4_CLUSTERS_PER_GROUP(sb). This can happen when clusters_per_group < blocksize * 8 and the tail of the bitmap is not properly filled by 1s which happened e.g. when ancient kernels have grown the filesystem.
Signed-off-by: Jan Kara jack@suse.cz Signed-off-by: Theodore Ts'o tytso@mit.edu Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/ext4/mballoc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -1555,7 +1555,7 @@ static int mb_find_extent(struct ext4_bu ex->fe_len += 1 << order; }
- if (ex->fe_start + ex->fe_len > (1 << (e4b->bd_blkbits + 3))) { + if (ex->fe_start + ex->fe_len > EXT4_CLUSTERS_PER_GROUP(e4b->bd_sb)) { /* Should never happen! (but apparently sometimes does?!?) */ WARN_ON(1); ext4_error(e4b->bd_sb, "corruption or bug in mb_find_extent "