[PATCH] lsm:fix a missing-check bug in smack_sb_eat_lsm_opts()

[Al Viro]

On Fri, Apr 16, 2021 at 05:53:03PM +0800,  Zhongjun Tan wrote:

> @@ -710,13 +711,14 @@ static int smack_sb_eat_lsm_opts(char *options, void **mnt_opts)
>  		token = match_opt_prefix(from, len, &arg);
>  		if (token != Opt_error) {
>  			arg = kmemdup_nul(arg, from + len - arg, GFP_KERNEL);
> +			if (!arg) {
> +				rc = -ENOMEM;
> +				goto free_mnt_opts;
>  			rc = smack_add_opt(token, arg, mnt_opts);

			if (arg)
	  			rc = smack_add_opt(token, arg, mnt_opts);
			else
				rc = -ENOMEM;

and no other changes are needed anywhere...