linux-fbdev.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: dri-devel <dri-devel@lists.freedesktop.org>,
	Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"Maciej W. Rozycki" <macro@orcam.me.uk>,
	Daniel Vetter <daniel@ffwll.ch>,
	syzbot <syzbot+1f29e126cf461c4de3b3@syzkaller.appspotmail.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Colin King <colin.king@canonical.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jani Nikula <jani.nikula@intel.com>,
	Jiri Slaby <jirislaby@kernel.org>,
	syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
	"Antonino A. Daplas" <adaplas@gmail.com>
Subject: Re: [PATCH] video: fbdev: vga16fb: fix OOB write in vga16fb_imageblit()
Date: Fri, 14 May 2021 10:37:47 -0700	[thread overview]
Message-ID: <CAHk-=whN=zrJ8BOLaGsJDH8d3sXLEoXA2DVsCq40OAUc1npOOw@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wguwhFpjhyMtDaH2hhjoV62gDgByC=aPyTrW9CkM5hqvA@mail.gmail.com>

On Fri, May 14, 2021 at 10:29 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> So why not just say "that clearly already doesn't work, so make it
> explicitly not permitted"?

IOW, something like this would seem fairly simple and straightforward:

  diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
  index 01645e87b3d5..f24e627b7402 100644
  --- a/drivers/tty/vt/vt.c
  +++ b/drivers/tty/vt/vt.c
  @@ -1171,8 +1171,13 @@ static inline int resize_screen(struct
vc_data *vc, int width, int height,
          /* Resizes the resolution of the display adapater */
          int err = 0;

  -       if (vc->vc_mode != KD_GRAPHICS && vc->vc_sw->con_resize)
  +       if (vc->vc_sw->con_resize) {
  +               // If we have a resize function but are in KD_GRAPHICS mode,
  +               // we can't actually do a resize and need to error out.
  +               if (vc->vc_mode == KD_GRAPHICS)
  +                       return -EINVAL;
                  err = vc->vc_sw->con_resize(vc, width, height, user);
  +       }

          return err;
   }

not tested, but it looks ObviouslyCorrect(tm), and since we know the
old case didn't work right, it seems very safe to do.

           Linus

  reply	other threads:[~2021-05-14 17:38 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-02-19 17:33 BUG: unable to handle kernel paging request at ffffc90000669000, IP: [<ffffffff8139d84a>] bitfill_un Tommi Rantala
2019-12-10 16:38 ` BUG: unable to handle kernel paging request in sys_imageblit syzbot
2020-06-19  4:56   ` syzbot
2019-12-27  7:13 ` BUG: unable to handle kernel paging request in vga16fb_imageblit syzbot
2020-05-08  7:07 ` BUG: unable to handle kernel paging request in vga16fb_imageblit (2) syzbot
2021-05-01 20:31   ` [syzbot] " syzbot
2021-05-02  1:53   ` syzbot
2021-05-03 13:41     ` Tetsuo Handa
2021-05-07 11:09       ` Tetsuo Handa
2021-05-14 16:19         ` [PATCH] video: fbdev: vga16fb: fix OOB write in vga16fb_imageblit() Tetsuo Handa
2021-05-14 17:29           ` Linus Torvalds
2021-05-14 17:37             ` Linus Torvalds [this message]
2021-05-14 18:23               ` Linus Torvalds
2021-05-14 20:25             ` Maciej W. Rozycki
2021-05-14 20:32               ` Linus Torvalds
2021-05-14 21:10                 ` Linus Torvalds
2021-05-15  7:43                   ` [PATCH v2] tty: vt: always invoke vc->vc_sw->con_resize callback Tetsuo Handa
2021-05-15 16:21                     ` Maciej W. Rozycki
2021-05-15 16:32                       ` Maciej W. Rozycki
2021-05-15 16:41                         ` Linus Torvalds
2021-05-17 13:13                           ` Daniel Vetter
2021-05-15 16:11                 ` [PATCH] video: fbdev: vga16fb: fix OOB write in vga16fb_imageblit() Maciej W. Rozycki
2021-05-17 13:07                 ` Daniel Vetter
2021-05-17 13:10                   ` Daniel Vetter
2021-05-15  0:45               ` Tetsuo Handa
2020-05-12  6:55 ` BUG: unable to handle kernel paging request in bitfill_aligned syzbot
2020-10-06  8:18 ` BUG: unable to handle kernel paging request in cfb_imageblit syzbot
2020-12-18 15:26   ` syzbot
2020-12-18 15:27     ` Dmitry Vyukov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAHk-=whN=zrJ8BOLaGsJDH8d3sXLEoXA2DVsCq40OAUc1npOOw@mail.gmail.com' \
    --to=torvalds@linux-foundation.org \
    --cc=adaplas@gmail.com \
    --cc=b.zolnierkie@samsung.com \
    --cc=colin.king@canonical.com \
    --cc=daniel@ffwll.ch \
    --cc=dri-devel@lists.freedesktop.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=jani.nikula@intel.com \
    --cc=jirislaby@kernel.org \
    --cc=linux-fbdev@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=macro@orcam.me.uk \
    --cc=penguin-kernel@i-love.sakura.ne.jp \
    --cc=syzbot+1f29e126cf461c4de3b3@syzkaller.appspotmail.com \
    --cc=syzkaller-bugs@googlegroups.com \
    --subject='Re: [PATCH] video: fbdev: vga16fb: fix OOB write in vga16fb_imageblit()' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).