Re: [PATCH AUTOSEL 6.18-6.12] ext4: reject mount if clusters/inodes per group are not 8-aligned

[sashiko-bot@kernel.org]

> From: Baokun Li <libaokun@linux.alibaba.com>
> 
> [ Upstream commit d42dc7726a003262b73ffef2b744ff57a5488799 ]
> 
> 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>
> Signed-off-by: Sasha Levin <sashal@kernel.org>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261019135441.1420968-395-sashal@kernel.org?part=1