On 2020/07/15 18:48, Dan Carpenter wrote:
>> @@ -216,7 +216,7 @@ static void bit_clear_margins(struct vc_data *vc, struct fb_info *info,
>> region.color = color;
>> region.rop = ROP_COPY;
>>
>> - if (rw && !bottom_only) {
>> + if ((int) rw > 0 && !bottom_only) {
>> region.dx = info->var.xoffset + rs;
> ^^^^^^^^^^^^^^^^^^^^^^
>
> If you choose a very high positive "rw" then this addition can overflow.
> info->var.xoffset comes from the user and I don't think it's checked...
Well, I think it would be checked by "struct fb_ops"->check_var hook.
For example, vmw_fb_check_var() has
if ((var->xoffset + var->xres) > par->max_width ||
(var->yoffset + var->yres) > par->max_height) {
DRM_ERROR("Requested geom can not fit in framebuffer\n");
return -EINVAL;
}
check. Of course, there might be integer overflow in that check...
Having sanity check at caller of "struct fb_ops"->check_var might be nice.
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