Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Mon, 4 Apr 2022 17:52:05 +0200 | Subject | Re: [PATCH 6/7] video: fbdev: arkfb: Error out if 'pixclock' equals zero |
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On Mon, Apr 4, 2022 at 3:10 PM Zheyu Ma <zheyuma97@gmail.com> 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. > > The following log reveals it: > > [ 76.603696] divide error: 0000 [#1] PREEMPT SMP KASAN PTI > [ 76.603712] RIP: 0010:arkfb_set_par+0x10fc/0x24f0 > [ 76.603762] Call Trace: > [ 76.603764] <TASK> > [ 76.603773] fb_set_var+0x604/0xeb0 > [ 76.603827] do_fb_ioctl+0x234/0x670 > [ 76.603873] fb_ioctl+0xdd/0x130 > [ 76.603881] do_syscall_64+0x3b/0x90 > > Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Thanks for your patch!
> --- a/drivers/video/fbdev/arkfb.c > +++ b/drivers/video/fbdev/arkfb.c > @@ -566,6 +566,9 @@ static int arkfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info) > { > int rv, mem, step; > > + if (!var->pixclock) > + return -EINVAL;
When passed an invalid value, .check_var() is supposed to round up the invalid to a valid value, if possible.
> + > /* Find appropriate format */ > rv = svga_match_format (arkfb_formats, var, NULL); > if (rv < 0)
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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