Re: [PATCH] iio: buffer: Fix double-free in iio_buffers_alloc_sysfs_and_mask()

[Andy Shevchenko]

On Tue, Oct 12, 2021 at 2:37 PM Alexandru Ardelean
<ardeleanalex@xxxxxxxxx> wrote:
>
> On Tue, Oct 12, 2021 at 12:18 PM Yang Yingliang
> <yangyingliang@xxxxxxxxxx> wrote:
> >
> > When __iio_buffer_alloc_sysfs_and_mask() failed, 'unwind_idx' should be
> > set to 'i - 1' to prevent double-free when cleanup resources.
> >
> > BUG: KASAN: double-free or invalid-free in __iio_buffer_free_sysfs_and_mask+0x32/0xb0 [industrialio]
> > Call Trace:
> >  kfree+0x117/0x4c0
> >  __iio_buffer_free_sysfs_and_mask+0x32/0xb0 [industrialio]
> >  iio_buffers_alloc_sysfs_and_mask+0x60d/0x1570 [industrialio]
> >  __iio_device_register+0x483/0x1a30 [industrialio]
> >  ina2xx_probe+0x625/0x980 [ina2xx_adc]
> >
>
> Makes sense.
> Thanks for the catch.
>
> Reviewed-by: Alexandru Ardelean <ardeleanalex@xxxxxxxxx>

...

> >                 ret = __iio_buffer_alloc_sysfs_and_mask(buffer, indio_dev, i);
> >                 if (ret) {
> > -                       unwind_idx = i;
> > +                       unwind_idx = i - 1;
> >                         goto error_unwind_sysfs_and_mask;

I prefer to see

- for (; unwind_idx >= 0; unwind_idx--) {
+ while (unwind_idx--)

instead.

> >                 }
> >         }

-- 
With Best Regards,
Andy Shevchenko