RE: [PATCH v2] exfat: zero the reserved fields of file and stream extension dentries

["Sungjong Seo" <sj1557.seo@samsung.com>]

> From exFAT specification, the reserved fields should initialize
> to zero and should not use for any purpose.
> 
> If create a new dentry set in the UNUSED dentries, all fields
> had been zeroed when allocating cluster to parent directory.
> 
> But if create a new dentry set in the DELETED dentries, the
> reserved fields in file and stream extension dentries may be
> non-zero. Because only the valid bit of the type field of the
> dentry is cleared in exfat_remove_entries(), if the type of
> dentry is different from the original(For example, a dentry that
> was originally a file name dentry, then set to deleted dentry,
> and then set as a file dentry), the reserved fields is non-zero.
> 
> So this commit initializes the dentry to 0 before createing file
> dentry and stream extension dentry.
> 
> Signed-off-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
> Reviewed-by: Andy Wu <Andy.Wu@sony.com>
> Reviewed-by: Aoyama Wataru <wataru.aoyama@sony.com>

Looks good. Thanks for your patch.
Reviewed-by: Sungjong Seo <sj1557.seo@samsung.com>

> ---
>  fs/exfat/dir.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/exfat/dir.c b/fs/exfat/dir.c
> index 077944d3c2c0..84572e11cc05 100644
> --- a/fs/exfat/dir.c
> +++ b/fs/exfat/dir.c
> @@ -420,6 +420,7 @@ static void exfat_set_entry_type(struct exfat_dentry
> *ep, unsigned int type)
>  static void exfat_init_stream_entry(struct exfat_dentry *ep,
>  		unsigned int start_clu, unsigned long long size)
>  {
> +	memset(ep, 0, sizeof(*ep));
>  	exfat_set_entry_type(ep, TYPE_STREAM);
>  	if (size == 0)
>  		ep->dentry.stream.flags = ALLOC_FAT_CHAIN;
> @@ -457,6 +458,7 @@ void exfat_init_dir_entry(struct exfat_entry_set_cache
> *es,
>  	struct exfat_dentry *ep;
> 
>  	ep = exfat_get_dentry_cached(es, ES_IDX_FILE);
> +	memset(ep, 0, sizeof(*ep));
>  	exfat_set_entry_type(ep, type);
>  	exfat_set_entry_time(sbi, ts,
>  			&ep->dentry.file.create_tz,
> --
> 2.34.1