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Sat, 8 Aug 2026 17:07:18 +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 3/5] s390/vfio-ap: Fix use of wrong lock in mdev probe function Date: Sat, 8 Aug 2026 13:07:10 -0400 Message-ID: <20260808170712.839066-4-akrowiak@linux.ibm.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260808170712.839066-1-akrowiak@linux.ibm.com> References: <20260808170712.839066-1-akrowiak@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: mizJpq5wg1SRAPkJIGn-j68Ptjvt9EnM X-Authority-Analysis: v=2.4 cv=J86aKgnS c=1 sm=1 tr=0 ts=6a77624a cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==: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-ORIG-GUID: mizJpq5wg1SRAPkJIGn-j68Ptjvt9EnM X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODA4MDE0NiBTYWx0ZWRfX6r5CDk+8WwP1 lKxGJO4wCC+cNW1v4UHUUFKQ973J/wUf4MrgMbZAJ4Eh2F2F8IcC3FKvmYnvYzB8pO6qil8zRU6 3NTsrinqOBevI1aUyhUQoba2Us+wISxv7szBhwwyrFu0tuGwoTBEaiLqKz4SQnb6p3cQuhYC1Bo /RJCF243zxFSLoDylz4zhngebfK1HnUcg4o9+iKFhyotdig4kVBSLCvpen8g8ym5fwQussaSbyA VtV5KrVS2uZK34xvGNg+59W04PZ1fZ84RXjp3UgrcJUH4b+xd5vkjVlSHkimO8N9lFjrAGnV/Mp OeWtgAmIcksKSVpJmFb5KMqjpx5yXVrQUPs+8ZWwozJ3uYofi124iNdALoFl0KPfseClSGdxEUN 4lC3nloQygqVn4QaCqdbzsQhmagjccGysWKKrowJ1Oh5Aj34MXMhl3ovjcE0+jPu7UkY1JmgV3x d6hzucMh9eT3S1vaVng== X-Proofpoint-Spam-Info: AW1haW4tMjYwODA4MDE0NiBTYWx0ZWRfXwAxH70ALHyjA CZd6UTXWJqVv8AJ6+KMi4IvKK7doVbSbb/sdQWuvj4iEx+0rITI3Gsp0b/HwnR172i54a8dM1WK dj2/Cfe8VznXHpzYQTxrQU3ncp8XFX0= 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=2026-08-08_06,2026-08-07_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 priorityscore=1501 suspectscore=0 malwarescore=0 adultscore=0 phishscore=0 impostorscore=0 lowpriorityscore=0 bulkscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608080146 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