static int uvesafb_setcmap(struct fb_cmap *cmap, struct fb_info *info)
{
	struct uvesafb_pal_entry *entries;
	int shift = 16 - dac_width;
	int i, err = 0;

	if (info->var.bits_per_pixel == 8) {
		if (cmap->start + cmap->len > info->cmap.start +
 		    info->cmap.len || cmap->start < info->cmap.start)
 			return -EINVAL;
 
		entries = kmalloc(sizeof(*entries) * cmap->len, GFP_KERNEL);
 		if (!entries)
 			return -ENOMEM;
 
		for (i = 0; i < cmap->len; i++) {
			entries[i].red   = cmap->red[i]   >> shift;
			entries[i].green = cmap->green[i] >> shift;
			entries[i].blue  = cmap->blue[i]  >> shift;
			entries[i].pad   = 0;
		}
		err = uvesafb_setpalette(entries, cmap->len, cmap->start, info);
		kfree(entries);
	} else {
		/*
		 * For modes with bpp > 8, we only set the pseudo palette in
		 * the fb_info struct. We rely on uvesafb_setcolreg to do all
		 * sanity checking.
		 */
		for (i = 0; i < cmap->len; i++) {
			err |= uvesafb_setcolreg(cmap->start + i, cmap->red[i],
						cmap->green[i], cmap->blue[i],
						0, info);
		}
	}
	return err;
}

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.