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Message-ID: <2023041308-nerd-dry-98a6@gregkh>
Date: Thu, 13 Apr 2023 14:47:58 +0200
From: Greg KH <gregkh@...uxfoundation.org>
To: Zheng Hacker <hackerzheng666@...il.com>
Cc: Yongqin Liu <yongqin.liu@...aro.org>,
John Stultz <jstultz@...gle.com>,
Zheng Wang <zyytlz.wz@....com>,
Sumit Semwal <sumit.semwal@...aro.org>, arnd@...db.de,
linux-kernel@...r.kernel.org, 1395428693sheep@...il.com,
alex000young@...il.com, Mauro Carvalho Chehab <mchehab@...nel.org>
Subject: Re: [PATCH] misc: hisi_hikey_usb: Fix use after free bug in
hisi_hikey_usb_remove due to race condition
On Thu, Apr 13, 2023 at 07:12:07PM +0800, Zheng Hacker wrote:
> Yongqin Liu <yongqin.liu@...aro.org> 于2023年4月13日周四 18:55写道:
> >
> > Hi, Zheng
> >
> > On Thu, 13 Apr 2023 at 16:08, Zheng Hacker <hackerzheng666@...il.com> wrote:
> > >
> > > Friendly ping about the bug.
> >
> > Sorry, wasn't aware of this message before,
> >
> > Could you please help share the instructions to reproduce the problem
> > this change fixes?
> >
>
> Hi Yongqin,
>
> Thanks for your reply. This bug is found by static analysis. There is no PoC.
>
> >From my personal experience, triggering race condition bugs stably in
> the kernel needs some tricks.
> For example, you can insert some sleep-time code to slow down the
> thread until the related object is freed.
> Besides, you can use gdb to control the time window. Also, there are
> some other tricks as [1] said.
>
> As for the reproduction, this attack vector requires that the attacker
> can physically access the device.
> When he/she unplugs the usb, the remove function is triggered, and if
> the set callback is invoked, there might be a race condition.
How does the removal of the USB device trigger a platform device
removal?
Are you sure this can be triggered by some other way other than manually
unloading the driver?
thanks,
greg k-h
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