linux-kernel - Re: [PATCH] pstore: Fix passing zero to 'PTR

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Message-ID: <202012011215.B9BF24A6D@keescook>
Date:   Tue, 1 Dec 2020 12:16:20 -0800
From:   Kees Cook <keescook@...omium.org>
To:     YueHaibing <yuehaibing@...wei.com>
Cc:     anton@...msg.org, ccross@...roid.com, tony.luck@...el.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] pstore: Fix passing zero to 'PTR_ERR' warning

On Sat, Oct 31, 2020 at 01:59:31PM +0800, YueHaibing wrote:
> Fix smatch warning:
> 
> fs/pstore/platform.c:320 allocate_buf_for_compression() warn: passing zero to 'PTR_ERR'
> 
> crypto_alloc_comp() never return NULL, use IS_ERR
> instead of IS_ERR_OR_NULL to fix this.
> 
> Signed-off-by: YueHaibing <yuehaibing@...wei.com>

Hmm, well, if I get back a NULL ctx, I still can't use it, so I prefer
to remain overly defensive in this code.

Thanks for looking in to it, though! If you see some more compelling
reason to do this, let me know.

-Kees

> ---
>  fs/pstore/platform.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index 36714df37d5d..b7a2a2a31dee 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -315,7 +315,7 @@ static void allocate_buf_for_compression(void)
>  	}
>  
>  	ctx = crypto_alloc_comp(zbackend->name, 0, 0);
> -	if (IS_ERR_OR_NULL(ctx)) {
> +	if (IS_ERR(ctx)) {
>  		kfree(buf);
>  		pr_err("crypto_alloc_comp('%s') failed: %ld\n", zbackend->name,
>  		       PTR_ERR(ctx));
> -- 
> 2.17.1
> 

-- 
Kees Cook