linux-kernel - Re: [PATCH] fbmem: don't allow too huge resolutions

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAMuHMdWbSUGRGAVi-17C3hyDBZnGLAsmbAs+wXPHiCNWWLbMpA@mail.gmail.com>
Date:   Tue, 31 Aug 2021 19:19:27 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Tetsuo Handa <penguin-kernel@...ove.sakura.ne.jp>
Cc:     Daniel Vetter <daniel.vetter@...ll.ch>,
        syzbot <syzbot+04168c8063cfdde1db5e@...kaller.appspotmail.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Colin King <colin.king@...onical.com>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Linux Fbdev development list <linux-fbdev@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        syzkaller-bugs@...glegroups.com,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH] fbmem: don't allow too huge resolutions

Hi Handa-san,

On Tue, Aug 31, 2021 at 5:24 PM Tetsuo Handa
<penguin-kernel@...ove.sakura.ne.jp> wrote:
> On 2021/08/31 15:48, Geert Uytterhoeven wrote:
> > Furthermore, this restricts the virtual frame buffer size on 64-bit,
> > too, while graphics cards can have much more than 4 GiB of RAM.
>
> Excuse me, but do you mean that some hardware allows allocating more than
> UINT_MAX bytes of memory for kernel frame buffer drivers?

While smem_len is u32 (there have been complaints about such
limitations on 64-bit platforms as far as 10 years ago), I see no
reason why a graphics card with more than 4 GiB of RAM would not be
able to provide a very large virtual screen.

Of course e.g. vga16fb cannot, as it is limited to 64 KiB.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-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