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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Dan Carpenter <dan.carpenter@oracle.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	syzbot <syzbot+04168c8063cfdde1db5e@syzkaller.appspotmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Colin King <colin.king@canonical.com>,
	DRI Development <dri-devel@lists.freedesktop.org>,
	Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Masahiro Yamada <masahiroy@kernel.org>,
	syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] BUG: unable to handle kernel paging request in vga16fb_fillrect
Date: Mon, 30 Aug 2021 17:00:49 +0200	[thread overview]
Message-ID: <CAMuHMdUtjd7Uf9VPEEztL+raasLdRqfMN55S8B8Nqoh0vxuk1g@mail.gmail.com> (raw)
In-Reply-To: <CAMuHMdWLTPBatefOgdVpfcqQoBw-D1F-_+-+23WdoQfwBcrz6A@mail.gmail.com>

Hi Tetsuo,

On Mon, Aug 30, 2021 at 4:53 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Mon, Aug 30, 2021 at 4:38 PM Tetsuo Handa
> <penguin-kernel@i-love.sakura.ne.jp> wrote:
> > On 2021/08/30 23:30, Geert Uytterhoeven wrote:
> > > The highest possible value of maxmem inside vga16fb_check_var()
> > > is 65536.
> >
> > Yes.
> >
> > >
> > > So I believe
> > >
> > >     if (array_size(vxres, vyres) > maxmem)
> > >
> > > should work fine.
> >
> > My intent is to check at common path than individual module so that we don't
> > need to add same check to every module. Same approach is proposed at
> > https://lkml.kernel.org/r/1630294223-7225-1-git-send-email-tcs_kernel@tencent.com .
>
> Which I believe is wrong.
> Thanks for the pointer, I will reply to the actual patch...

Upon second look, that patch is not really wrong, as the check happens
after calling into info->fbops->fb_check_var().

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

      reply	other threads:[~2021-08-30 15:01 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-14  5:16 [syzbot] BUG: unable to handle kernel paging request in vga16fb_fillrect syzbot
2021-08-30  0:24 ` Randy Dunlap
2021-08-30  2:27   ` Tetsuo Handa
2021-08-30  2:31     ` Randy Dunlap
2021-08-30 16:05       ` [PATCH] fbmem: don't allow too huge resolutions Tetsuo Handa
2021-08-31  6:48         ` Geert Uytterhoeven
2021-08-31 15:23           ` Tetsuo Handa
2021-08-31 16:20             ` Daniel Vetter
2021-08-31 17:19             ` Geert Uytterhoeven
2021-08-31 18:53               ` Daniel Vetter
2021-08-31 18:56                 ` Geert Uytterhoeven
2021-08-31 19:04                   ` Daniel Vetter
2021-09-01  1:14                     ` [PATCH v2] " Tetsuo Handa
2021-09-01  7:12                       ` Geert Uytterhoeven
2021-08-30 12:00     ` [syzbot] BUG: unable to handle kernel paging request in vga16fb_fillrect Geert Uytterhoeven
2021-08-30 13:00       ` Dan Carpenter
2021-08-30 13:37         ` Tetsuo Handa
2021-08-30 13:47           ` Dan Carpenter
2021-08-30 14:25             ` Tetsuo Handa
2021-08-30 14:29               ` Dan Carpenter
2021-08-30 14:30               ` Geert Uytterhoeven
2021-08-30 14:38                 ` Tetsuo Handa
2021-08-30 14:53                   ` Geert Uytterhoeven
2021-08-30 15:00                     ` Geert Uytterhoeven [this message]

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