static int uvesafb_pan_display(struct fb_var_screeninfo *var,
		struct fb_info *info)
{
#ifdef CONFIG_X86_32
	int offset;
	struct uvesafb_par *par = info->par;

	offset = (var->yoffset * info->fix.line_length + var->xoffset) / 4;

	/*
	 * It turns out it's not the best idea to do panning via vm86,
	 * so we only allow it if we have a PMI.
	 */
	if (par->pmi_start) {
		__asm__ __volatile__(
			"call *(%%edi)"
			: /* no return value */
			: "a" (0x4f07),         /* EAX */
			  "b" (0),              /* EBX */
			  "c" (offset),         /* ECX */
			  "d" (offset >> 16),   /* EDX */
			  "D" (&par->pmi_start));    /* EDI */
	}
#endif
	return 0;
}

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.