Re: [PATCH 1/2] ASoC: SOF: sof-client-probes: fix error codes in sof_probes_compr_copy()

Dan Carpenter
2022-07-06T10:33:13Z

On Wed, Jul 06, 2022 at 01:21:59PM +0300, Dan Carpenter wrote:
> On Wed, Jul 06, 2022 at 12:05:37PM +0300, Péter Ujfalusi wrote:
> >
> >
> > On 06/07/2022 10:23, Dan Carpenter wrote:
> > > This function tries to return the number of bytes that it was able to
> > > copy to the user. However, because there are multiple calls to
> > > copy_to_user() in a row that means the bytes are not necessarily
> > > consecutive so it's not useful. Just return -EFAULT instead.
> >
> > The function is copying data from a circular buffer to a use buffer.
> > The single copy_to_user() is used when we don't have wrapping, the
> > 'double' copy_to_user() is when we wrap, so first copy is from the end
> > of the buffer then we copy the data from the start of the buffer to get
> > all data.
>
> Ok. But the bugs in the original code are real. I will resend.

Actually that's not true. The bugs in the original code are something
that only affect users who deserve it? I might not resend. A fix would
look something like below?

regards,
dan carpenter

diff --git a/sound/soc/sof/sof-client-probes.c b/sound/soc/sof/sof-client-probes.c
index 1f1ea93a7fbf..32fa3186c295 100644
--- a/sound/soc/sof/sof-client-probes.c
+++ b/sound/soc/sof/sof-client-probes.c
@@ -398,9 +398,14 @@ static int sof_probes_compr_copy(struct snd_soc_component *component,
ret = copy_to_user(buf, ptr, count);
} else {
ret = copy_to_user(buf, ptr, n);
- ret += copy_to_user(buf + n, rtd->dma_area, count - n);
+ if (ret) {
+ ret += count - n;
+ goto done;
+ }
+ ret = copy_to_user(buf + n, rtd->dma_area, count - n);
}

+done:
if (ret)
return count - ret;
return count;