On Mon, Apr 4, 2022 at 3:10 PM Zheyu Ma <zheyuma97@xxxxxxxxx> 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@xxxxxxxxx>
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@xxxxxxxxxxxxxx
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
