linux-kernel - Re: [PATCH 1/2] hfs: fix potential refcnt problem of nls module

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Date:   Wed, 18 Apr 2018 10:10:56 -0700
From:   Viacheslav Dubeyko <slava@...eyko.com>
To:     Chengguang Xu <cgxu519@....com>, linux-fsdevel@...r.kernel.org
Cc:     dhowells@...hat.com, kstewart@...uxfoundation.org,
        gregkh@...uxfoundation.org, tglx@...utronix.de,
        pombredanne@...b.com, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/2] hfs: fix potential refcnt problem of nls module

On Tue, 2018-04-17 at 15:05 +0800, Chengguang Xu wrote:
> When specifying iocharset/codepage multiple times in a mount,
> current option parsing will cause inaccurate refcount of nls
> module. Hence, call unload_nls for previous one in this case.
> 
> Signed-off-by: Chengguang Xu <cgxu519@....com>


Looks good.

Reviewed-by: Vyacheslav Dubeyko <slava@...eyko.com>

Thanks,
Vyacheslav Dubeyko.


> ---
>  fs/hfs/super.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/hfs/super.c b/fs/hfs/super.c
> index 1738767..6a5f6fd 100644
> --- a/fs/hfs/super.c
> +++ b/fs/hfs/super.c
> @@ -329,8 +329,10 @@ static int parse_options(char *options, struct
> hfs_sb_info *hsb)
>  				return 0;
>  			}
>  			p = match_strdup(&args[0]);
> -			if (p)
> +			if (p) {
> +				unload_nls(hsb->nls_disk);
>  				hsb->nls_disk = load_nls(p);
> +			}
>  			if (!hsb->nls_disk) {
>  				pr_err("unable to load codepage
> \"%s\"\n", p);
>  				kfree(p);
> @@ -344,8 +346,10 @@ static int parse_options(char *options, struct
> hfs_sb_info *hsb)
>  				return 0;
>  			}
>  			p = match_strdup(&args[0]);
> -			if (p)
> +			if (p) {
> +				unload_nls(hsb->nls_io);
>  				hsb->nls_io = load_nls(p);
> +			}
>  			if (!hsb->nls_io) {
>  				pr_err("unable to load iocharset
> \"%s\"\n", p);
>  				kfree(p);