From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: "Maciej W. Rozycki" <macro@orcam.me.uk>,
Linus Torvalds <torvalds@linux-foundation.org>
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>,
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: Sat, 15 May 2021 09:45:11 +0900 [thread overview]
Message-ID: <543ead9f-08d2-cc9d-e569-78a479378e62@i-love.sakura.ne.jp> (raw)
In-Reply-To: <alpine.DEB.2.21.2105142150460.3032@angie.orcam.me.uk>
On 2021/05/15 5:25, Maciej W. Rozycki wrote:
> NB for fbcon the usual ioctl to resize the console is FBIOPUT_VSCREENINFO
> rather than VT_RESIZEX; fbset(8) uses it, and I actually experimented with
> it and a TGA-like (SFB+) framebuffer when at my lab last time, as Linux is
> kind enough to know how to fiddle with its clockchip. It works just fine.
fbcon_update_vcs() from FBIOPUT_VSCREENINFO is no-op if vc->vc_mode != KD_TEXT
(which is equivalent to "if vc->vc_mode == KD_GRAPHICS" because KD_TEXT0/KD_TEXT1
are treated as KD_TEXT). Then, maybe it is OK to let resize_screen() return -EINVAL
in order to make vc_do_resize() request fail if vc->vc_mode == KD_GRAPHICS.
> Overall I think it does make sense to resize the text console at any
> time, even if the visible console (VT) chosen is in the graphics mode, as
> my understanding (and experience at least with vgacon) is that resizing
> the console applies globally across all the VTs. So the intent of the
> original change appears valid to me, and the choice not to reprogram the
> visible console and only store the settings for a future use if it's in
> the graphics mode correct.
>
> Which means any bug triggered here needs to be fixed elsewhere rather
> than by making the request fail.
Since syzbot does not trigger this problem with Linus's patch, I think we can
try Linus's patch with
pr_info_once("Resizing text console while in graphical mode is ignored. Please report if you need this.\n");
added in order to see if somebody wants "only store the settings for a future use".
next prev parent reply other threads:[~2021-05-15 0:45 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
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 [this message]
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
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