diff options
| author | Baokun Li <libaokun@linux.alibaba.com> | 2026-06-08 19:11:48 +0800 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2026-07-21 11:26:39 -0400 |
| commit | d42dc7726a003262b73ffef2b744ff57a5488799 (patch) | |
| tree | a645445b3e8f8cb7b3af4f14fb917eed917a82c4 | |
| parent | a13c140cc289c0b7b3770bce5b3ad42ab35074aa (diff) | |
ext4: reject mount if clusters/inodes per group are not 8-aligned
The block and inode bitmap checksums are computed over a whole number of
bytes: ext4_inode_bitmap_csum_*() use EXT4_INODES_PER_GROUP(sb) >> 3 and
ext4_block_bitmap_csum_*() use EXT4_CLUSTERS_PER_GROUP(sb) / 8 as the
length passed to ext4_chksum().
If s_inodes_per_group or s_clusters_per_group is not a multiple of 8, the
trailing fractional bits are excluded from the checksum. Those bits are
then unprotected, and any incremental csum update path that assumes a
byte-aligned bitmap can compute a checksum inconsistent with the full
recalculation, corrupting the on-disk bitmap checksum.
Reject such filesystems at mount time by adding the missing " & 7"
alignment checks alongside the existing range validation.
Suggested-by: Theodore Ts'o <tytso@mit.edu>
Link: https://patch.msgid.link/h3n7jlfhyna64dn5o76qxcspnhxdddcs6crpxftmy7gnl7b3sx@jenszfpcsnit
Reported-by: Sashiko <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260508121539.4174601-1-libaokun%40linux.alibaba.com?part=10
Signed-off-by: Baokun Li <libaokun@linux.alibaba.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20260608111150.827117-2-libaokun@linux.alibaba.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | fs/ext4/super.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 245f67d10ded..229eb509905f 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4475,8 +4475,9 @@ static int ext4_handle_clustersize(struct super_block *sb) sbi->s_cluster_bits = 0; } sbi->s_clusters_per_group = le32_to_cpu(es->s_clusters_per_group); - if (sbi->s_clusters_per_group > sb->s_blocksize * 8) { - ext4_msg(sb, KERN_ERR, "#clusters per group too big: %lu", + if (sbi->s_clusters_per_group > sb->s_blocksize * 8 || + sbi->s_clusters_per_group & 7) { + ext4_msg(sb, KERN_ERR, "invalid #clusters per group: %lu", sbi->s_clusters_per_group); return -EINVAL; } @@ -5308,8 +5309,9 @@ static int ext4_block_group_meta_init(struct super_block *sb, int silent) return -EINVAL; } if (sbi->s_inodes_per_group < sbi->s_inodes_per_block || - sbi->s_inodes_per_group > sb->s_blocksize * 8) { - ext4_msg(sb, KERN_ERR, "invalid inodes per group: %lu\n", + sbi->s_inodes_per_group > sb->s_blocksize * 8 || + sbi->s_inodes_per_group & 7) { + ext4_msg(sb, KERN_ERR, "invalid inodes per group: %lu", sbi->s_inodes_per_group); return -EINVAL; } |