static ssize_t oz_cdev_read(struct file *filp, char __user *buf, size_t count,
		loff_t *fpos)
{
	int n;
	int ix;

	struct oz_pd *pd;
	struct oz_serial_ctx *ctx;

	spin_lock_bh(&g_cdev.lock);
	pd = g_cdev.active_pd;
	if (pd)
		oz_pd_get(pd);
	spin_unlock_bh(&g_cdev.lock);
	if (pd == NULL)
		return -1;
	ctx = oz_cdev_claim_ctx(pd);
	if (ctx == NULL)
		goto out2;
	n = ctx->rd_in - ctx->rd_out;
	if (n < 0)
		n += OZ_RD_BUF_SZ;
	if (count > n)
		count = n;
	ix = ctx->rd_out;
	n = OZ_RD_BUF_SZ - ix;
	if (n > count)
		n = count;
	if (copy_to_user(buf, &ctx->rd_buf[ix], n)) {
		count = 0;
		goto out1;
	}
	ix += n;
	if (ix == OZ_RD_BUF_SZ)
		ix = 0;
	if (n < count) {
		if (copy_to_user(&buf[n], ctx->rd_buf, count-n)) {
			count = 0;
			goto out1;
		}
		ix = count-n;
	}
	ctx->rd_out = ix;
out1:
	oz_cdev_release_ctx(ctx);
out2:
	oz_pd_put(pd);
	return count;
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.