On Wed, Feb 10, 2021 at 11:24:23PM -0800, Joe Perches wrote:
> On Thu, 2021-02-11 at 10:11 +0300, Dan Carpenter wrote:
> > On Wed, Feb 10, 2021 at 02:28:54PM -0800, Drew Fustini wrote:
> > > + ret = strncpy_from_user(buf, user_buf, PINMUX_MAX_NAME * 2);
> > > + if (ret < 0) {
> > > + dev_err(pctldev->dev, "failed to copy buffer from userspace");
> > > + goto free_gname;
> > > + }
> > > + buf[len-1] = '\0';
> > > +
> > > + ret = sscanf(buf, "%s %s", fname, gname);
> > > + if (ret != 2) {
> > > + dev_err(pctldev->dev, "expected format: <function-name>
> > > <group-name>");
> > > + goto free_gname;
> >
> > We need a "ret = -EINVAL;" before the goto. sscanf doesn't return error
> > codes. Normally we would write it like so:
> >
> > if (sscanf(buf, "%s %s", fname, gname) != 2) {
> > dev_err(pctldev->dev, "expected format: <function-name>
> > <group-name>");
> > ret = -EINVAL;
> > goto free_gname;
> > }
> >
> > I'm going to write a Smatch check for this today.
>
> It's a pretty frequently used style:
>
> $ git grep -P '\w+\s*=\s+sscanf\b' | wc -l
> 327
Yeah. That's true. I looked through a couple of those and they were
fine. (Sample size 2) But the other format is more common.
$ git grep sscanf | grep = | wc -l
803
I have written a Smatch check to complain whenever we propogate the
return value from sscanf. I'll let you know tomorrow how that goes.
I should write another check which says "On this error path, we know
sscanf was not equal to the value we wanted but we are still returning
success".
regards,
dan carpenter
