Re: [PATCH -next] ALSA: pcm: replace simple_strtoul to kstrtoul

[Takashi Iwai <tiwai@xxxxxxx>]

On Fri, 30 Aug 2024 10:01:35 +0200,
Hongbo Li wrote:
> 
> As mentioned in [1], "...simple_strtol(), simple_strtoll(),
> simple_strtoul(), and simple_strtoull() functions explicitly
> ignore overflows, which may lead to unexpected results in callers."
> Hence, the use of those functions is discouraged.
> 
> This patch replace the use of the simple_strtoul with the safer
> alternatives kstrtoul.
> 
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#simple-strtol-simple-strtoll-simple-strtoul-simple-strtoull
> 
> Signed-off-by: Hongbo Li <lihongbo22@xxxxxxxxxx>
> ---
>  sound/core/pcm_memory.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/core/pcm_memory.c b/sound/core/pcm_memory.c
> index 8e4c68e3bbd0..fea8bed02604 100644
> --- a/sound/core/pcm_memory.c
> +++ b/sound/core/pcm_memory.c
> @@ -185,6 +185,7 @@ static void snd_pcm_lib_preallocate_proc_write(struct snd_info_entry *entry,
>  	char line[64], str[64];
>  	size_t size;
>  	struct snd_dma_buffer new_dmab;
> +	int ret;
>  
>  	guard(mutex)(&substream->pcm->open_mutex);
>  	if (substream->runtime) {
> @@ -193,8 +194,10 @@ static void snd_pcm_lib_preallocate_proc_write(struct snd_info_entry *entry,
>  	}
>  	if (!snd_info_get_line(buffer, line, sizeof(line))) {
>  		snd_info_get_str(str, line, sizeof(str));
> -		size = simple_strtoul(str, NULL, 10) * 1024;
> -		if ((size != 0 && size < 8192) || size > substream->dma_max) {
> +		ret = kstrtoul(str, 10, &size);
> +		size *= 1024;
> +		if ((ret != 0) || (size != 0 && size < 8192) ||

The parentheses around "ret != 0" is superfluous.
And you can set the value to buffer->error, too.

That said, it's better not to put the ret value check in that if
block, but put another check right after kstrtoul() call.


thanks,

Takashi