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Fri, 31 May 2024 01:31:19 +0000 Received: from pps.filterd (phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com (8.17.1.19/8.17.1.19) with ESMTP id 44UMutAn016282; Fri, 31 May 2024 01:31:18 GMT Received: from pps.reinject (localhost [127.0.0.1]) by phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTPS id 3yc50t980r-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Fri, 31 May 2024 01:31:18 +0000 Received: from phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com (phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 44V1SKNe027418; Fri, 31 May 2024 01:31:17 GMT Received: from bur-virt-x6-2-100.us.oracle.com (bur-virt-x6-2-100.us.oracle.com [10.153.92.40]) by phxpaimrmta02.imrmtpd1.prodappphxaev1.oraclevcn.com (PPS) with ESMTPS id 3yc50t96yw-14 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Fri, 31 May 2024 01:31:17 +0000 From: Ross Philipson To: linux-kernel@vger.kernel.org, x86@kernel.org, linux-integrity@vger.kernel.org, linux-doc@vger.kernel.org, linux-crypto@vger.kernel.org, kexec@lists.infradead.org, linux-efi@vger.kernel.org, iommu@lists.linux-foundation.org Cc: ross.philipson@oracle.com, dpsmith@apertussolutions.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, dave.hansen@linux.intel.com, ardb@kernel.org, mjg59@srcf.ucam.org, James.Bottomley@hansenpartnership.com, peterhuewe@gmx.de, jarkko@kernel.org, jgg@ziepe.ca, luto@amacapital.net, nivedita@alum.mit.edu, herbert@gondor.apana.org.au, davem@davemloft.net, corbet@lwn.net, ebiederm@xmission.com, dwmw2@infradead.org, baolu.lu@linux.intel.com, kanth.ghatraju@oracle.com, andrew.cooper3@citrix.com, trenchboot-devel@googlegroups.com Subject: [PATCH v9 13/19] tpm: Protect against locality counter underflow Date: Thu, 30 May 2024 18:03:25 -0700 Message-Id: <20240531010331.134441-14-ross.philipson@oracle.com> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20240531010331.134441-1-ross.philipson@oracle.com> References: <20240531010331.134441-1-ross.philipson@oracle.com> Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1039,Hydra:6.0.650,FMLib:17.12.28.16 definitions=2024-05-30_21,2024-05-30_01,2024-05-17_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 spamscore=0 suspectscore=0 adultscore=0 phishscore=0 malwarescore=0 mlxlogscore=999 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2405010000 definitions=main-2405310010 X-Proofpoint-GUID: HNDubto-grwXgietQQlmdfNwuYKjAoD2 X-Proofpoint-ORIG-GUID: HNDubto-grwXgietQQlmdfNwuYKjAoD2 From: "Daniel P. Smith" 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 Signed-off-by: Ross Philipson Reported-by: Kanth Ghatraju 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 176cd8dbf1db..7c1761bd6000 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);