[qemu-xen stable-4.14] tests: tpm: Skip over pcrUpdateCounter byte in result comparison

[patchbot@xxxxxxx]

commit d2581f25ec28666b5c6e6ffa4adbffde33181387
Author:     Stefan Berger <stefanb@xxxxxxxxxxxxxxxxxx>
AuthorDate: Tue Jul 7 16:16:25 2020 -0400
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Wed Sep 2 19:06:19 2020 -0500

    tests: tpm: Skip over pcrUpdateCounter byte in result comparison
    
    The TPM 2 code in libtpms was fixed to handle the PCR 'TCB group' according
    to the PCClient profile. The change of the PCRs belonging to the 'TCB group'
    now affects the pcrUpdateCounter in the TPM2_PCRRead() responses where its
    value is now different (typically lower by '1') than what it was before. To
    not fail the tests, we skip the comparison of the 14th byte, which
    represents the pcrUpdateCounter.
    
    Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxx>
    Reviewed-by: Marc-André Lureau <marcandre.lureau@xxxxxxxxxx>
    Message-id: 20200707201625.4177419-3-stefanb@xxxxxxxxxxxxxxxxxx
    (cherry picked from commit df8a7568932e4c3c930fdfeb228dd72b4bb71a1f)
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 tests/qtest/tpm-util.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tests/qtest/tpm-util.c b/tests/qtest/tpm-util.c
index 34efae8f18..58a9593745 100644
--- a/tests/qtest/tpm-util.c
+++ b/tests/qtest/tpm-util.c
@@ -139,7 +139,11 @@ void tpm_util_pcrread(QTestState *s, tx_func *tx,
 
     tx(s, tpm_pcrread, sizeof(tpm_pcrread), buffer, sizeof(buffer));
 
-    g_assert_cmpmem(buffer, exp_resp_size, exp_resp, exp_resp_size);
+    /* skip pcrUpdateCounter (14th byte) in comparison */
+    g_assert(exp_resp_size >= 15);
+    g_assert_cmpmem(buffer, 13, exp_resp, 13);
+    g_assert_cmpmem(&buffer[14], exp_resp_size - 14,
+                    &exp_resp[14], exp_resp_size - 14);
 }
 
 bool tpm_util_swtpm_has_tpm2(void)
--
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