From: Linus Torvalds <torvalds@linux-foundation.org>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Jani Nikula <jani.nikula@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
dri-devel <dri-devel@lists.freedesktop.org>,
Colin King <colin.king@canonical.com>,
Jiri Slaby <jirislaby@kernel.org>,
syzbot <syzbot+1f29e126cf461c4de3b3@syzkaller.appspotmail.com>,
"Maciej W. Rozycki" <macro@orcam.me.uk>
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
next prev parent reply other threads:[~2021-05-14 17:38 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
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
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