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

[Takashi Iwai <tiwai@suse.de>]

On Sat, 31 Aug 2024 03:19:06 +0200,
Hongbo Li wrote:
> 
> 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@huawei.com>
> >> ---
> >>   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;
> }

Yes, something like that.


thanks,

Takashi