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ext4: make sanity check in mballoc more strict

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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
This commit is contained in:
Jan Kara 2019-04-06 18:33:06 -04:00 committed by Theodore Ts'o
parent fb20375109
commit 31562b954b
1 changed files with 1 additions and 1 deletions
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2
fs/ext4/mballoc.c
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@ -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 "