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

[Hongbo Li <lihongbo22@xxxxxxxxxx>]

buffer->error

On 2024/8/30 16:22, Takashi Iwai wrote:
> 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.
Do you mean :

buffer->error = kstrtoul(str, 10, &size);
if (buffer->error != 0)
    return;
size *= 1024;
if (size != 0 && size < 8192)) {
    buffer->error = -EINVAL;
    return;
}

Thanks,
Hongbo
> thanks,
>
> Takashi