linux-kernel - Re: [PATCH] mtd: fix use-after-free in mtd release

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Message-ID: <ZMKJRNDoQV8p0DH4@smile.fi.intel.com>
Date:   Thu, 27 Jul 2023 18:12:04 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Alexander Usyskin <alexander.usyskin@...el.com>
Cc:     Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Tomas Winkler <tomas.winkler@...el.com>,
        Vitaly Lubart <vitaly.lubart@...el.com>,
        Zhang Xiaoxu <zhangxiaoxu5@...wei.com>
Subject: Re: [PATCH] mtd: fix use-after-free in mtd release

On Thu, Jul 27, 2023 at 05:57:58PM +0300, Alexander Usyskin wrote:
> I case of partition device_unregister in mtd_device_release

In

device_unregister()
mtd_device_release()

> calls mtd_release which frees mtd_info structure for partition.

mtd_release()

> All code after device_unregister in mtd_device_release thus

device_unregister()
mtd_device_release()

> works already freed memory.

uses?

> Move part of code to mtd_release and restict mtd->dev cleanup

mtd_release()

> to non-partion object.
> For partition object such cleanup have no sense as partition
> mtd_info is removed.
> 
> Cc: Miquel Raynal <miquel.raynal@...tlin.com>
> Cc: Zhang Xiaoxu <zhangxiaoxu5@...wei.com>
> Fixes: 19bfa9ebebb5 ("mtd: use refcount to prevent corruption")

Closes: ?

-- 
With Best Regards,
Andy Shevchenko