linux-kernel - [PATCH] tpm: set TPM_CHIP_FLAG

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Message-ID: <20241029223647.35209-1-jarkko@kernel.org>
Date: Wed, 30 Oct 2024 00:36:47 +0200
From: Jarkko Sakkinen <jarkko@...nel.org>
To: Peter Huewe <peterhuewe@....de>,
	Jarkko Sakkinen <jarkko@...nel.org>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Jerry Snitselaar <jsnitsel@...hat.com>
Cc: stable@...r.kernel.org,
	Mike Seo <mikeseohyungjin@...il.com>,
	linux-integrity@...r.kernel.org (open list:TPM DEVICE DRIVER),
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] tpm: set TPM_CHIP_FLAG_SUSPENDED early

Setting TPM_CHIP_FLAG_SUSPENDED in the end of tpm_pm_suspend() can be racy
according to the bug report, as this leaves window for tpm_hwrng_read() to
be called while the operation is in progress. Move setting of the flag
into the beginning.

Cc: stable@...r.kernel.org # v6.4+
Fixes: 99d464506255 ("tpm: Prevent hwrng from activating during resume")
Reported-by: Mike Seo <mikeseohyungjin@...il.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219383
Signed-off-by: Jarkko Sakkinen <jarkko@...nel.org>
---
 drivers/char/tpm/tpm-interface.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
index 8134f002b121..3f96bc8b95df 100644
--- a/drivers/char/tpm/tpm-interface.c
+++ b/drivers/char/tpm/tpm-interface.c
@@ -370,6 +370,8 @@ int tpm_pm_suspend(struct device *dev)
 	if (!chip)
 		return -ENODEV;
 
+	chip->flags |= TPM_CHIP_FLAG_SUSPENDED;
+
 	if (chip->flags & TPM_CHIP_FLAG_ALWAYS_POWERED)
 		goto suspended;
 
@@ -390,8 +392,6 @@ int tpm_pm_suspend(struct device *dev)
 	}
 
 suspended:
-	chip->flags |= TPM_CHIP_FLAG_SUSPENDED;
-
 	if (rc)
 		dev_err(dev, "Ignoring error %d while suspending\n", rc);
 	return 0;
-- 
2.47.0