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From: "Daniel P. Smith" <dpsmith@apertussolutions.com>
To: Jason Gunthorpe <jgg@ziepe.ca>,
	Jarkko Sakkinen <jarkko@kernel.org>,
	Sasha Levin <sashal@kernel.org>,
	Lino Sanfilippo <l.sanfilippo@kunbus.com>,
	linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: "Daniel P. Smith" <dpsmith@apertussolutions.com>,
	Ross Philipson <ross.philipson@oracle.com>,
	Kanth Ghatraju <kanth.ghatraju@oracle.com>,
	Peter Huewe <peterhuewe@gmx.de>
Subject: [PATCH 1/3] tpm: protect against locality counter underflow
Date: Wed, 31 Jan 2024 12:08:21 -0500	[thread overview]
Message-ID: <20240131170824.6183-2-dpsmith@apertussolutions.com> (raw)
In-Reply-To: <20240131170824.6183-1-dpsmith@apertussolutions.com>

Commit 933bfc5ad213 introduced the use of a locality counter to control when a
locality request is allowed to be sent to the TPM. In the commit, the counter
is indiscriminately decremented. Thus creating a situation for an integer
underflow of the counter.

Signed-off-by: Daniel P. Smith <dpsmith@apertussolutions.com>
Signed-off-by: Ross Philipson <ross.philipson@oracle.com>
Reported-by: Kanth Ghatraju <kanth.ghatraju@oracle.com>
Fixes: 933bfc5ad213 ("tpm, tpm: Implement usage counter for locality")
---
 drivers/char/tpm/tpm_tis_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/char/tpm/tpm_tis_core.c b/drivers/char/tpm/tpm_tis_core.c
index 1b350412d8a6..4176d3bd1f04 100644
--- a/drivers/char/tpm/tpm_tis_core.c
+++ b/drivers/char/tpm/tpm_tis_core.c
@@ -180,7 +180,8 @@ static int tpm_tis_relinquish_locality(struct tpm_chip *chip, int l)
 	struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
 
 	mutex_lock(&priv->locality_count_mutex);
-	priv->locality_count--;
+	if (priv->locality_count > 0)
+		priv->locality_count--;
 	if (priv->locality_count == 0)
 		__tpm_tis_relinquish_locality(priv, l);
 	mutex_unlock(&priv->locality_count_mutex);
-- 
2.30.2


       reply	other threads:[~2024-01-31 17:08 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20240131170824.6183-1-dpsmith@apertussolutions.com>
2024-01-31 17:08 ` Daniel P. Smith [this message]
2024-02-01 22:21   ` [PATCH 1/3] tpm: protect against locality counter underflow Jarkko Sakkinen
2024-02-02  3:08     ` Lino Sanfilippo
2024-02-12 20:05       ` Jarkko Sakkinen
2024-02-19 17:54         ` Daniel P. Smith
2024-02-20 18:42       ` Alexander Steffen
2024-02-20 19:04         ` Jarkko Sakkinen
2024-02-20 20:54         ` Lino Sanfilippo
2024-02-20 22:23           ` Jarkko Sakkinen
2024-02-20 23:19             ` Lino Sanfilippo
2024-02-21  0:40               ` Jarkko Sakkinen
2024-02-23  1:58             ` Daniel P. Smith
2024-02-23 12:58               ` Jarkko Sakkinen
2024-02-25 11:23                 ` Daniel P. Smith
2024-02-26  9:39                   ` Jarkko Sakkinen
2024-02-20 22:26           ` Jarkko Sakkinen
2024-02-20 22:31             ` Jarkko Sakkinen
2024-02-20 23:26               ` Lino Sanfilippo
2024-02-21  0:42                 ` Jarkko Sakkinen
2024-02-21 12:37               ` James Bottomley
2024-02-21 19:43                 ` Jarkko Sakkinen
2024-02-21 19:45                   ` Jarkko Sakkinen
2024-02-22  9:06                   ` James Bottomley
2024-02-22 23:49                     ` Jarkko Sakkinen
2024-02-23  1:57                   ` Daniel P. Smith
2024-02-23 20:40                     ` Jarkko Sakkinen
2024-02-23 20:42                       ` Jarkko Sakkinen
2024-02-23  1:57               ` Daniel P. Smith
2024-02-23 20:50                 ` Jarkko Sakkinen
2024-02-20 22:57             ` ross.philipson
2024-02-20 23:10               ` Jarkko Sakkinen
2024-02-20 23:13                 ` Jarkko Sakkinen
2024-02-23  1:56           ` Daniel P. Smith
2024-02-23 20:44             ` Jarkko Sakkinen
2024-02-24  2:34             ` Lino Sanfilippo
2024-02-26  9:38               ` Jarkko Sakkinen
2024-02-23  1:55         ` Daniel P. Smith
2024-02-26 12:43           ` Alexander Steffen
2024-02-24  2:06         ` Lino Sanfilippo
2024-02-23  0:01   ` Jarkko Sakkinen
2024-01-31 17:08 ` [PATCH 2/3] tpm: ensure tpm is in known state at startup Daniel P. Smith
2024-02-01 22:33   ` Jarkko Sakkinen
2024-02-19 19:17     ` Daniel P. Smith
2024-02-19 20:17       ` Jarkko Sakkinen
2024-01-31 17:08 ` [PATCH 3/3] tpm: make locality request return value consistent Daniel P. Smith
2024-02-01 22:49   ` Jarkko Sakkinen
2024-02-19 20:29     ` Daniel P. Smith
2024-02-19 20:45       ` Jarkko Sakkinen
2024-02-20 18:57       ` Alexander Steffen

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