static int h2s_send_rst_stream(struct h2c *h2c, struct h2s *h2s)
{
	struct buffer *res;
	char str[13];
	int ret;

	if (!h2s || h2s->st == H2_SS_CLOSED)
		return 1;

	/* RFC7540#5.4.2: To avoid looping, an endpoint MUST NOT send a
	 * RST_STREAM in response to a RST_STREAM frame.
	 */
	if (h2c->dft == H2_FT_RST_STREAM) {
		ret = 1;
		goto ignore;
	}

	if (h2c_mux_busy(h2c, h2s)) {
		h2s->flags |= H2_SF_BLK_MBUSY;
		return 0;
	}

	res = h2_get_buf(h2c, &h2c->mbuf);
	if (!res) {
		h2c->flags |= H2_CF_MUX_MALLOC;
		h2s->flags |= H2_SF_BLK_MROOM;
		return 0;
	}

	/* len: 4, type: 3, flags: none */
	memcpy(str, "\x00\x00\x04\x03\x00", 5);
	write_n32(str + 5, h2s->id);
	write_n32(str + 9, h2s->errcode);
	ret = bo_istput(res, ist2(str, 13));

	if (unlikely(ret <= 0)) {
		if (!ret) {
			h2c->flags |= H2_CF_MUX_MFULL;
			h2s->flags |= H2_SF_BLK_MROOM;
			return 0;
		}
		else {
			h2c_error(h2c, H2_ERR_INTERNAL_ERROR);
			return 0;
		}
	}

 ignore:
	h2s->flags |= H2_SF_RST_SENT;
	h2s_close(h2s);
	return ret;
}

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.