linux-kernel - Re: [PATCH] pinctrl: sunxi: fix use-after-free in sunxi_pmx

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Date:   Fri, 22 Jan 2021 14:15:36 +0800
From:   "liu xiang" <liu.xiang@...ngsmart.com>
To:     "Maxime Ripard" <maxime@...no.tech>
Cc:     "linux-gpio" <linux-gpio@...r.kernel.org>,
        "linus.walleij" <linus.walleij@...aro.org>, "wens" <wens@...e.org>,
        "jernej.skrabec" <jernej.skrabec@...l.net>,
        "linux-arm-kernel" <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel" <linux-kernel@...r.kernel.org>,
        "liuxiang_1999" <liuxiang_1999@....com>
Subject: Re: [PATCH] pinctrl: sunxi: fix use-after-free in sunxi_pmx_free()

> Hi,

> On Tue, Jan 19, 2021 at 02:29:08PM +0800, Liu Xiang wrote:
> When CONFIG_REGULATOR is not set, sunxi_pmx_request() always return
> success. Even a group of pins call sunxi_pmx_request(), the refcount
> is only 1. This can cause a use-after-free warning in sunxi_pmx_free().
> To solve this problem, go to err path if regulator_get() return NULL
> or error.
> 
> Signed-off-by: Liu Xiang <liu.xiang@...ngsmart.com>

> Is there any drawback to depending on CONFIG_REGULATOR?

> Given that we need those regulators enabled anyway, I guess we could
> just select or depends on it
>
> Maxime


Yes, I think so. But CONFIG_REGULATOR is not enabled by default now.
So I can find this problem during startup.