Re: [PATCH 2/3] ext4: reject casefolded names that fold to ".", "..", or empty

[sashiko-bot@kernel.org]

> Filenames consisting solely of ignorable Unicode characters fold to
> empty strings, while names with leading dots and ignorable characters
> fold to "." or "..". Allowing such names to be created or looked up in
> casefolded directories collides with on-disk "." and ".." entries (which
> triggers EXT4_ERROR_INODE in ext4_lookup()) and introduces duplicate
> entries that e2fsck flags as corruption.
> 
> Skip casefolding when the lookup name is literally "." or "..", reject
> any non-dot names that fold to "", ".", or ".." in
> ext4_fname_setup_ci_filename(), and fall back to opaque byte hashing in
> ext4fs_dirhash() when utf8_casefold() yields "", ".", or "..".
> 
> Fixes: b886ee3e778e ("ext4: Support case-insensitive file name lookups")
> Co-developed-by: Dmitry Torokhov <dtor@google.com>
> Signed-off-by: Dmitry Torokhov <dtor@google.com>
> Signed-off-by: Sarthak Kukreti <sarthakkukreti@google.com>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261113065332.929085-1-sarthakkukreti@google.com?part=2