linux-kernel - [PATCH 5.4 152/184] tpm: vtpm_proxy: Avoid reading host log when using a virtual device

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Message-Id: <20210510101955.103862731@linuxfoundation.org>
Date:   Mon, 10 May 2021 12:20:46 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Stefan Berger <stefanb@...ux.ibm.com>,
        Jarkko Sakkinen <jarkko@...nel.org>
Subject: [PATCH 5.4 152/184] tpm: vtpm_proxy: Avoid reading host log when using a virtual device

From: Stefan Berger <stefanb@...ux.ibm.com>

commit 9716ac65efc8f780549b03bddf41e60c445d4709 upstream.

Avoid allocating memory and reading the host log when a virtual device
is used since this log is of no use to that driver. A virtual
device can be identified through the flag TPM_CHIP_FLAG_VIRTUAL, which
is only set for the tpm_vtpm_proxy driver.

Cc: stable@...r.kernel.org
Fixes: 6f99612e2500 ("tpm: Proxy driver for supporting multiple emulated TPMs")
Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>
Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/char/tpm/eventlog/common.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/char/tpm/eventlog/common.c
+++ b/drivers/char/tpm/eventlog/common.c
@@ -107,6 +107,9 @@ void tpm_bios_log_setup(struct tpm_chip
 	int log_version;
 	int rc = 0;
 
+	if (chip->flags & TPM_CHIP_FLAG_VIRTUAL)
+		return;
+
 	rc = tpm_read_log(chip);
 	if (rc < 0)
 		return;