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Commit 71478ef6 authored by Jan Kara's avatar Jan Kara Committed by Greg Kroah-Hartman
Browse files

ext4: make sanity check in mballoc more strict 



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: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 001fe0da

fs/ext4/mballoc.c

+1 −1
Original line number Diff line number Diff line
@@ -1539,7 +1539,7 @@ static int mb_find_extent(struct ext4_buddy *e4b, int block, 
		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 "