linux-kernel - Re: [PATCH AUTOSEL 4.19 592/671] USB: usb-skeleton: fix use-after-free after driver unbind

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Message-ID: <20200123142252.GE1706@sasha-vm>
Date:   Thu, 23 Jan 2020 09:22:52 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     Johan Hovold <johan@...nel.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org
Subject: Re: [PATCH AUTOSEL 4.19 592/671] USB: usb-skeleton: fix
 use-after-free after driver unbind

On Fri, Jan 17, 2020 at 11:21:16AM +0100, Johan Hovold wrote:
>On Thu, Jan 16, 2020 at 12:03:50PM -0500, Sasha Levin wrote:
>> From: Johan Hovold <johan@...nel.org>
>>
>> [ Upstream commit 6353001852776e7eeaab4da78922d4c6f2b076af ]
>>
>> The driver failed to stop its read URB on disconnect, something which
>> could lead to a use-after-free in the completion handler after driver
>> unbind in case the character device has been closed.
>>
>> Fixes: e7389cc9a7ff ("USB: skel_read really sucks royally")
>> Signed-off-by: Johan Hovold <johan@...nel.org>
>> Link: https://lore.kernel.org/r/20191009170944.30057-3-johan@kernel.org
>> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>> Signed-off-by: Sasha Levin <sashal@...nel.org>
>
>This one isn't needed in any stable tree. As we discussed before, the
>skeleton driver is only there for documentation purposes.

I'll drop this, but I'm curious: doesn't this mean that users will build
on buggy example code?

-- 
Thanks,
Sasha