Re: [PATCH] udf: fix potential refcnt problem of nls module

From: Jan Kara
Date: Wed Feb 28 2018 - 07:36:15 EST


On Sun 25-02-18 21:25:07, Chengguang Xu wrote:
> When specifiying iocharset multiple times in a mount
> or once/multiple in a remount, current option parsing
> may cause inaccurate refcount of nls module.
> Also, in the failure cleanup of option parsing,
> the condition of calling unload_nls is not sufficient.
>
> Signed-off-by: Chengguang Xu <cgxu519@xxxxxxxxxx>
> ---
>
> Hi Jan,
>
> I found this issue by checking code so now post the fix for rewiew,
> but sorry I did't get enough resource to fully test it, I can only
> make sure the fix can successfuly comiple with no error.

Thanks for the patch. I have added it to my tree.

Honza

>
> fs/udf/super.c | 12 ++++++++----
> 1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/fs/udf/super.c b/fs/udf/super.c
> index 7b27b06..7e73a98 100644
> --- a/fs/udf/super.c
> +++ b/fs/udf/super.c
> @@ -523,8 +523,12 @@ static int udf_parse_options(char *options, struct udf_options *uopt,
> break;
> #ifdef CONFIG_UDF_NLS
> case Opt_iocharset:
> - uopt->nls_map = load_nls(args[0].from);
> - uopt->flags |= (1 << UDF_FLAG_NLS_MAP);
> + if (!remount) {
> + if (uopt->nls_map)
> + unload_nls(uopt->nls_map);
> + uopt->nls_map = load_nls(args[0].from);
> + uopt->flags |= (1 << UDF_FLAG_NLS_MAP);
> + }
> break;
> #endif
> case Opt_uignore:
> @@ -2082,8 +2086,8 @@ error_out:
> for (i = 0; i < sbi->s_partitions; i++)
> udf_free_partition(&sbi->s_partmaps[i]);
> #ifdef CONFIG_UDF_NLS
> - if (UDF_QUERY_FLAG(sb, UDF_FLAG_NLS_MAP))
> - unload_nls(sbi->s_nls_map);
> + if (uopt.nls_map)
> + unload_nls(uopt.nls_map);
> #endif
> if (!(sb->s_flags & MS_RDONLY))
> udf_close_lvid(sb);
> --
> 1.8.3.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR