linux-kernel - Re: [PATCH] iio: buffer: Fix double-free in iio_buffers_alloc_sysfs_and

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Date:   Tue, 12 Oct 2021 23:30:21 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Alexandru Ardelean <ardeleanalex@...il.com>
Cc:     Yang Yingliang <yangyingliang@...wei.com>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-iio <linux-iio@...r.kernel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Jonathan Cameron <jic23@...nel.org>
Subject: Re: [PATCH] iio: buffer: Fix double-free in iio_buffers_alloc_sysfs_and_mask()

On Tue, Oct 12, 2021 at 2:37 PM Alexandru Ardelean
<ardeleanalex@...il.com> wrote:
>
> On Tue, Oct 12, 2021 at 12:18 PM Yang Yingliang
> <yangyingliang@...wei.com> 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@...il.com>

...

> >                 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