Copy the bounds checking from encode_message() to decode_message().

This patch addresses the following concerns.  Ensure that there is
enough space for at least one header so that we don't have a negative
size later.

	if (msg_hdr_len < sizeof(*trans_hdr))

Ensure that we have enough space to read the next header from the
msg->data.

	if (msg_len > msg_hdr_len - sizeof(*trans_hdr))
		return -EINVAL;

Check that the trans_hdr->len is not below the minimum size:

	if (hdr_len < sizeof(*trans_hdr))

This minimum check ensures that we don't corrupt memory in
decode_passthrough() when we do.

	memcpy(out_trans->data, in_trans->data, len - sizeof(in_trans->hdr));

And finally, use size_add() to prevent an integer overflow:

	if (size_add(msg_len, hdr_len) > msg_hdr_len)

Fixes: 129776ac ("accel/qaic: Add control path")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@quicinc.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Cc: stable@vger.kernel.org # 6.4.x
Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Link: https://patchwork.freedesktop.org/patch/msgid/ZK0Q5nbLyDO7kJa+@moroto