Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Thu, 3 Feb 2022 08:53:53 +0100 | Subject | Re: [PATCH v2 RESEND 3] video: fbdev: cirrusfb: check pixclock to avoid divide by zero |
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Hi George,
CC Helge, linux-fbdev
On Wed, Feb 2, 2022 at 7:23 PM George Kennedy <george.kennedy@oracle.com> wrote: > Do a sanity check on pixclock value to avoid divide by zero. > > If the pixclock value is zero, the cirrusfb driver will round up > pixclock to get the derived frequency as close to maxclock as > possible. > > Syzkaller reported a divide error in cirrusfb_check_pixclock. > > divide error: 0000 [#1] SMP KASAN PTI > CPU: 0 PID: 14938 Comm: cirrusfb_test Not tainted 5.15.0-rc6 #1 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2 > RIP: 0010:cirrusfb_check_var+0x6f1/0x1260 > > Call Trace: > fb_set_var+0x398/0xf90 > do_fb_ioctl+0x4b8/0x6f0 > fb_ioctl+0xeb/0x130 > __x64_sys_ioctl+0x19d/0x220 > do_syscall_64+0x3a/0x80 > entry_SYSCALL_64_after_hwframe+0x44/0xae > > Cc: <stable@vger.kernel.org> # 5.4.y > Reported-by: syzkaller <syzkaller@googlegroups.com> > Signed-off-by: George Kennedy<george.kennedy@oracle.com> > Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org> > --- > Hi Andrew, can you pick this patch up? Some of the fbdev drivers have > maintainers but the cirrusfb.c is basically orphaned. I sent this patch > in Oct and again in Dec and no one picked it up. Geert has reviewed it. > Obviously the original code just crashed so this shouldn't be > controversial. > > v2: Geert says that instead of just returning an error, this is supposed > to find a valid pixclock and use that. > > RESEND: Added the Reviewed by: and Cc: <stable@vger.kernel.org>
This is already queued in the fbdev for-next branch[1], as announced by Helge in [2].
[1] https://git.kernel.org/pub/scm/linux/kernel/git/deller/linux-fbdev.git/commit/?h=for-next&id=5c6f402bdcf9e7239c6bc7087eda71ac99b31379 [2] https://lore.kernel.org/all/e1e5b7d1-ea09-6e28-9c39-45b983734a85@gmx.de/
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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
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