Re: [PATCH v1 1/3] PM / sysfs: Convert to use sysfs_streq()

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Wed, 2017-11-15 at 11:32 +0100, Pavel Machek wrote:
> Hi!
> 
> > ...instead of custom approach.
> > 

> >  			     const char * buf, size_t n)
> >  {
> > -	char *cp;
> > -	int len = n;
> > -
> > -	cp = memchr(buf, '\n', n);
> > -	if (cp)
> > -		len = cp - buf;
> >  	device_lock(dev);
> > -	if (len == sizeof ctrl_auto - 1 && strncmp(buf, ctrl_auto,
> > len) == 0)
> > +	if (sysfs_streq(buf, ctrl_auto))
> >  		pm_runtime_allow(dev);
> > -	else if (len == sizeof ctrl_on - 1 && strncmp(buf, ctrl_on,
> > len) == 0)
> > +	else if (sysfs_streq(buf, ctrl_on))
> >  		pm_runtime_forbid(dev);
> >  	else
> >  		n = -EINVAL;
> 
> Are you sure?

Yes.

>  _streq does not get passed size_t n; how does it
> guarantee no out-of-bounds access?

It's guaranteed by kernfs for every attribute that relies on it.

https://www.spinics.net/lists/kernel/msg2635067.html

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy