On Thu, Mar 01, 2018 at 02:10:17PM -0800, J Freyensee wrote:

.
.
.
I'm new to this area of the kernel, but I'm not getting these lines:

quoted

+	rc = tpm_transmit_cmd(chip, NULL, buf.data, PAGE_SIZE, 0, 0, NULL);
+	tpm_buf_destroy(&buf);
  	if (rc <  0)

Why is this if() check not directly after the tpm_transmit_cmd() call that
sets rc?? Is it correct you want to destroy buf regardless of the
tpm_transmit_cmd() outcome?

quoted

  		return rc;
-
-	if (be16_to_cpu(cmd.header.out.tag) == TPM2_ST_NO_SESSIONS)
+	out = (struct tpm_output_header *)buf.data;

So buf has been destroyed, buf.data sill has something valid to assign to
out?

quoted

+	if (be16_to_cpu(out->tag) == TPM2_ST_NO_SESSIONS)
  		chip->flags |= TPM_CHIP_FLAG_TPM2;
  	return 0;

Thanks,
Jay

Nope it is a regression in the patch. Thank you :-) tpm_buf_destroy()
can be called if the response data is not needed other than everything
went OK (tpm_transmit_cmd() already digs this info).

/Jarkko
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