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Message-ID: <61c28865036cd40a96f2d1bb4c27fbbb08c2d3a5.camel@perches.com>
Subject: Re: [PATCH] iio: buffer: Fix double-free in
 iio_buffers_alloc_sysfs_and_mask()
From:   Joe Perches <joe@perches.com>
To:     Andy Shevchenko <andy.shevchenko@gmail.com>,
        Alexandru Ardelean <ardeleanalex@gmail.com>
Cc:     Yang Yingliang <yangyingliang@huawei.com>,
        LKML <linux-kernel@vger.kernel.org>,
        linux-iio <linux-iio@vger.kernel.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Jonathan Cameron <jic23@kernel.org>
Date:   Tue, 12 Oct 2021 10:43:23 -0700
In-Reply-To: <CAHp75Vf+DHNxiP5HzsKzzh5hFmr20P8SzOTnLXAvhC5Vb6hzMA@mail.gmail.com>
References: <20211012092513.1349295-1-yangyingliang@huawei.com>
         <CA+U=DsrHSwaiS7mT4rcHT_ZQwfPg+-Hwm-jkib11+m7W-VA_FQ@mail.gmail.com>
         <CAHp75Vf+DHNxiP5HzsKzzh5hFmr20P8SzOTnLXAvhC5Vb6hzMA@mail.gmail.com>
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On Tue, 2021-10-12 at 23:30 +0300, 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.
[]
> 
> I prefer to see
> 
> - for (; unwind_idx >= 0; unwind_idx--) {
> + while (unwind_idx--)

Not the same code as unwind_idx would be decremented before entering
the code block.

You'd want

	do {
		...
	} while (unwind_idx--);