linux-kernel - Re: [PATCH 4.19] fbmem: add margin check to fb_check

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Date:   Sat, 4 Sep 2021 10:12:43 +0800
From:   Dongliang Mu <mudongliangabcd@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     stable@...r.kernel.org,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        George Kennedy <george.kennedy@...cle.com>,
        syzbot+e5fd3e65515b48c02a30@...kaller.appspotmail.com,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Dhaval Giani <dhaval.giani@...cle.com>,
        Sasha Levin <sashal@...nel.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4.19] fbmem: add margin check to fb_check_caps()

On Fri, Sep 3, 2021 at 9:55 PM Greg KH <gregkh@...uxfoundation.org> wrote:
>
> On Thu, Sep 02, 2021 at 02:10:48PM +0800, Dongliang Mu wrote:
> > [ Upstream commit a49145acfb975d921464b84fe00279f99827d816 ]
> >
> > A fb_ioctl() FBIOPUT_VSCREENINFO call with invalid xres setting
> > or yres setting in struct fb_var_screeninfo will result in a
> > KASAN: vmalloc-out-of-bounds failure in bitfill_aligned() as
> > the margins are being cleared. The margins are cleared in
> > chunks and if the xres setting or yres setting is a value of
> > zero upto the chunk size, the failure will occur.
> >
> > Add a margin check to validate xres and yres settings.
> >
> > Note that, this patch needs special handling to backport it to linux
> > kernel 4.19, 4.14, 4.9, 4.4.
>
> Looks like this is already in the 4.4.283, 4.9.282, 4.14.246, and
> 4.19.206 kernel releases.  Can you check them to verify that it matches
> your backport as well?

Yes, I have seen them in these releases and they are fine to me.

>
> thanks,
>
> greg k-h