linux-kernel - Re: [PATCH] media:usb:cpia2: Properly check framebuffer mmap offsets

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Message-ID: <a1c55e7d-4710-70e9-f4d0-8fc155197f07@xs4all.nl>
Date:   Sat, 9 Nov 2019 12:39:43 +0100
From:   Hans Verkuil <hverkuil@...all.nl>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Omer Shalev <omerdeshalev@...il.com>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Kate Stewart <kstewart@...uxfoundation.org>,
        Richard Fontana <rfontana@...hat.com>,
        Allison Randal <allison@...utok.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media:usb:cpia2: Properly check framebuffer mmap offsets

Hi Greg,

On 11/8/19 9:49 PM, Greg Kroah-Hartman wrote:
> On Fri, Nov 08, 2019 at 09:50:36PM +0000, Omer Shalev wrote:
>> The cpai2 driver's mmap implementation wasn't properly check for all
>> possible offset values. Given a huge offset value , the calculation
>> start_offset + size can wrap around to a low value and pass the check
> 
> I thought we checked that in the core of the kernel now, to keep all
> drivers from not having to do this type of thing (as they obviously all
> forgot to.)  Why is this still needed here as well?

Where is that checked in the core? I couldn't find anything, but I might
have been looking in the wrong place.

Regards,

	Hans

> 
> thanks,
> 
> greg k-h
>