Re: [PATCH 6.6] ext4: filesystems without casefold feature cannot be mounted with siphash

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, Feb 07, 2025 at 12:37:03PM +0100, vgiraud.opensource@witekio.com wrote:
> From: Lizhi Xu <lizhi.xu@windriver.com>
> 
> commit 985b67cd86392310d9e9326de941c22fc9340eec upstream.
> 
> When mounting the ext4 filesystem, if the default hash version is set to
> DX_HASH_SIPHASH but the casefold feature is not set, exit the mounting.
> 
> Reported-by: syzbot+340581ba9dceb7e06fb3@syzkaller.appspotmail.com
> Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com>
> Link: https://patch.msgid.link/20240605012335.44086-1-lizhi.xu@windriver.com
> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
> Signed-off-by: Bruno VERNAY <bruno.vernay@se.com>
> Signed-off-by: Victor Giraud <vgiraud.opensource@witekio.com>
> ---
>  fs/ext4/super.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index f019ce64eba4..b69d791be846 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -3627,6 +3627,14 @@ int ext4_feature_set_ok(struct super_block *sb, int readonly)
>  	}
>  #endif
>  
> +	if (EXT4_SB(sb)->s_es->s_def_hash_version == DX_HASH_SIPHASH &&
> +	    !ext4_has_feature_casefold(sb)) {
> +		ext4_msg(sb, KERN_ERR,
> +			 "Filesystem without casefold feature cannot be "
> +			 "mounted with siphash");
> +		return 0;
> +	}
> +
>  	if (readonly)
>  		return 1;
>  
> -- 
> 2.34.1
> 
> 

Any specific reason you asked for just this one commit to be backported
and NOT the fix for this commit?

How did you test this?

ugh,

greg k-h