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Mon, 10 Aug 2026 19:23:01 +0000 (GMT) Received: from li-4c4c4544-004d-4810-8043-b7c04f423534.ibm.com.com (unknown [9.61.71.153]) by smtpav01.dal12v.mail.ibm.com (Postfix) with ESMTP; Mon, 10 Aug 2026 19:23:01 +0000 (GMT) From: Anthony Krowiak To: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: jjherne@linux.ibm.com, borntraeger@de.ibm.com, mjrosato@linux.ibm.com, pasic@linux.ibm.com, alex@shazbot.org, kwankhede@nvidia.com, fiuczy@linux.ibm.com, pbonzini@redhat.com, frankja@linux.ibm.com, imbrenda@linux.ibm.com, agordeev@linux.ibm.com, hca@linux.ibm.com, gor@linux.ibm.com, stable@vger.kernel.org Subject: [PATCH v2 3/8] s390/vfio-ap: Fix use of wrong lock in mdev probe function Date: Mon, 10 Aug 2026 15:22:52 -0400 Message-ID: <20260810192257.1208410-4-akrowiak@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260810192257.1208410-1-akrowiak@linux.ibm.com> References: <20260810192257.1208410-1-akrowiak@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Authority-Analysis: v=2.4 cv=XqfK/1F9 c=1 sm=1 tr=0 ts=6a7a2519 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=IOhVIQ1U7ISs0PSOFQMA:9 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODEwMDE2MiBTYWx0ZWRfX89VIYVWL6k9u U4DufLH/EYFhprFk1zg06J1Bc13taCG6RnQOI1hVrRjLssZEtqM3z/hNrgrC4c39TbmbiE1r1k/ Gl9fvTq981jIOW6T/twOEMaN8feDYHERgcdlqA3FcxEQx1DXcUQQvsF0bLwRcsWd7p8Yo0AmhN2 qLzND5TjP0Z4704yugfN2ma+63AgkcTof34QPXYircqLSnmlEJPKgwci86cGYKsff/ICLxzN6UN KcMdCvpTFCUgx5dEBq+5c5bAjJx+aujkKYYszUZSb1aht2u4po5OqNFfbFiq5rk9R+sP1ge3oux 3KgzVb+S5SdeONPydPs8ycU+c16RSjBTgkv162n3sR8eqWQpC8L0TNKqL7Y6FVZEaM+4vNRKxlf AiTLkGONa1tC2GFp/Wlnf4DQMURVSuUgpT0mJj8e5kk/raAgYmsQnQ35BmVP2EeV35u7FqvhzCS LpWn18oHCUbMaxXYClA== X-Proofpoint-ORIG-GUID: 8Cjv-eEuMRiZBTtPUt0UdhH5qf1Q58sW X-Proofpoint-GUID: 8Cjv-eEuMRiZBTtPUt0UdhH5qf1Q58sW X-Proofpoint-Spam-Info: AW1haW4tMjYwODEwMDE2MiBTYWx0ZWRfXxrjaF6RO2CXX 1nhqE7GENfl7lmqNP08zDJCOas2lLxaMu2BWicH9wQypudW/e3rjr2hoNFH9wOxGnBYsBldFhlY O1ozCmcdpxyCjEpKFJu2U4YLzzmCAU4= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-10_05,2026-08-10_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 spamscore=0 adultscore=0 malwarescore=0 clxscore=1015 suspectscore=0 priorityscore=1501 impostorscore=0 phishscore=0 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608100162 The vfio_ap_mdev_probe function uses the matrix_dev->mdevs_lock mutex to guard the add of a newly created ap_matrix_mdev object to the matrix_dev->mdev_list. This mutex does not protect against traversal of the list; its purpose is to guard against concurrent access to fields contained in an ap_matrix_mdev object. This could lead to kernel memory corruption or use-after-free if another mdev is created concurrently. The adding of an ap_matrix_mdev object to matrix_dev->mdev_list is now guarded by the matrix_dev->guests_lock which is the correct way to protect against concurrent mdev_list access. See the vfio-ap-locking.rst in the linux kernel tree. Fixes: 2c1ee8983aa3 ("s390/vfio-ap: prepare for dynamic update of guest's APCB on queue probe/remove") Cc: stable@vger.kernel.org Signed-off-by: Anthony Krowiak --- drivers/s390/crypto/vfio_ap_ops.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c index e382e5a1cb99..a472de00bc14 100644 --- a/drivers/s390/crypto/vfio_ap_ops.c +++ b/drivers/s390/crypto/vfio_ap_ops.c @@ -803,9 +803,9 @@ static int vfio_ap_mdev_probe(struct mdev_device *mdev) matrix_mdev->req_trigger = NULL; matrix_mdev->cfg_chg_trigger = NULL; dev_set_drvdata(&mdev->dev, matrix_mdev); - mutex_lock(&matrix_dev->mdevs_lock); + mutex_lock(&matrix_dev->guests_lock); list_add(&matrix_mdev->node, &matrix_dev->mdev_list); - mutex_unlock(&matrix_dev->mdevs_lock); + mutex_unlock(&matrix_dev->guests_lock); return 0; err_put_vdev: -- 2.53.0