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SubjectRe: [PATCH] iio: buffer: Fix double-free in iio_buffers_alloc_sysfs_and_mask()
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Hi,

On 2021/10/13 4:30, Andy Shevchenko wrote:
> On Tue, Oct 12, 2021 at 2:37 PM Alexandru Ardelean
> <ardeleanalex@gmail.com> wrote:
>> On Tue, Oct 12, 2021 at 12:18 PM Yang Yingliang
>> <yangyingliang@huawei.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@gmail.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 using while loop, 'unwind_idx =
iio_dev_opaque->attached_buffers_cnt - 1;' need
be changed.
I think my change is clear and simple, do I need resend a new version
with using while loop ?

Thanks,
Yang
>
>>> }
>>> }

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