From: Ondrej Zary <linux@zary.sk>
To: Zheyu Ma <zheyuma97@gmail.com>
Cc: Helge Deller <deller@gmx.de>,
Linux Fbdev development list <linux-fbdev@vger.kernel.org>,
DRI Development <dri-devel@lists.freedesktop.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 1/7] video: fbdev: i740fb: Error out if 'pixclock' equals zero
Date: Sun, 10 Apr 2022 11:02:13 +0200 [thread overview]
Message-ID: <202204101102.13505.linux@zary.sk> (raw)
In-Reply-To: <CAMhUBjmm6ADp2Fr89CCQNX5FnhmBBrwFE0EQ3sq7CLER0J3ZEg@mail.gmail.com>
On Friday 08 April 2022 03:58:10 Zheyu Ma wrote:
> On Fri, Apr 8, 2022 at 3:50 AM Helge Deller <deller@gmx.de> wrote:
> >
> > On 4/4/22 10:47, Zheyu Ma wrote:
> > > The userspace program could pass any values to the driver through
> > > ioctl() interface. If the driver doesn't check the value of 'pixclock',
> > > it may cause divide error.
> > >
> > > Fix this by checking whether 'pixclock' is zero in the function
> > > i740fb_check_var().
> > >
> > > The following log reveals it:
> > >
> > > divide error: 0000 [#1] PREEMPT SMP KASAN PTI
> > > RIP: 0010:i740fb_decode_var drivers/video/fbdev/i740fb.c:444 [inline]
> > > RIP: 0010:i740fb_set_par+0x272f/0x3bb0 drivers/video/fbdev/i740fb.c:739
> > > Call Trace:
> > > fb_set_var+0x604/0xeb0 drivers/video/fbdev/core/fbmem.c:1036
> > > do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1112
> > > fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1191
> > > vfs_ioctl fs/ioctl.c:51 [inline]
> > > __do_sys_ioctl fs/ioctl.c:874 [inline]
> > >
> > > Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
> >
> > Hello Zheyu,
> >
> > I've applied the patches #2-#7 of this series, but left
> > out this specific patch (for now).
> > As discussed on the mailing list we can try to come up with a
> > better fix (to round up the pixclock when it's invalid).
> > If not, I will apply this one later.
>
> I'm also looking forward to a more appropriate patch for this driver!
I was not able to reproduce it at first but finally found it: the monitor must be unplugged. If a valid EDID is present, fb_validate_mode() call in i740fb_check_var() will refuse zero pixclock.
Haven't found any obvious way to correct zero pixclock value. Most other drivers simply return -EINVAL.
> Thanks,
> Zheyu Ma
>
--
Ondrej Zary
next prev parent reply other threads:[~2022-04-10 9:02 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-04 8:47 [PATCH 0/7] Fix divide errors in fbdev drivers Zheyu Ma
2022-04-04 8:47 ` [PATCH 1/7] video: fbdev: i740fb: Error out if 'pixclock' equals zero Zheyu Ma
2022-04-07 19:49 ` Helge Deller
2022-04-08 1:58 ` Zheyu Ma
2022-04-10 9:02 ` Ondrej Zary [this message]
2022-04-11 6:18 ` Helge Deller
2022-04-04 8:47 ` [PATCH 2/7] video: fbdev: neofb: Fix the check of 'var->pixclock' Zheyu Ma
2022-04-04 8:47 ` [PATCH 3/7] video: fbdev: kyro: Error out if 'lineclock' equals zero Zheyu Ma
2022-04-04 8:47 ` [PATCH 4/7] video: fbdev: vt8623fb: Error out if 'pixclock' " Zheyu Ma
2022-04-04 11:47 ` Geert Uytterhoeven
2022-04-04 8:47 ` [PATCH 5/7] video: fbdev: tridentfb: " Zheyu Ma
2022-04-04 8:47 ` [PATCH 6/7] video: fbdev: arkfb: " Zheyu Ma
2022-04-04 15:52 ` Geert Uytterhoeven
2022-04-04 8:47 ` [PATCH 7/7] video: fbdev: s3fb: " Zheyu Ma
2022-04-04 15:52 ` Geert Uytterhoeven
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=202204101102.13505.linux@zary.sk \
--to=linux@zary.sk \
--cc=deller@gmx.de \
--cc=dri-devel@lists.freedesktop.org \
--cc=linux-fbdev@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=zheyuma97@gmail.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).