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Wed, 27 Aug 2025 21:08:29 +0000 (GMT) From: Matthew Rosato To: joro@8bytes.org, schnelle@linux.ibm.com Cc: will@kernel.org, robin.murphy@arm.com, gerald.schaefer@linux.ibm.com, jgg@ziepe.ca, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, stable@vger.kernel.org, Cam Miller Subject: [PATCH] iommu/s390: Fix memory corruption when using identity domain Date: Wed, 27 Aug 2025 17:08:27 -0400 Message-ID: <20250827210828.274527-1-mjrosato@linux.ibm.com> X-Mailer: git-send-email 2.50.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-TM-AS-GCONF: 00 X-Proofpoint-GUID: CL5xb0cttaozS9hlBWyRob2q_BkQTay2 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODIzMDAyMSBTYWx0ZWRfX+L1bAXC7oCdx jZ8CwhWkkZiRcM1GxOxw42sbFzHz45Nj37SD1CpR3wtN4xN3vlsXvPezox0oR89oVwVBYVr+4H0 zz9UmtzlpJsve2W3HJKcyKOC+bimXc0fUDH9vGo5xIVFEzCRQMvjaxh41mvboDb0zmpkV8aJA1N nvO9pYbKjk+QSkdzh9IQ9TjMY52aHCBVZhghkninoLlS5DMEjRtDYo0oVKNr4ES+R5RHnMTanDd zLbOJt70DMqmIYQEGOhGLqAsPqCfOPOAzFMZRzJfMWy7yllLtvgL3YbsR0gg3dlN2Tp04NuApqU pg7XhpSTSEyxqOlltKBEqlhtKMQKigieD0os97erOZK5KQG64H1goH2KJsh2lTRYZA0cKyu03ko vAZExXsA X-Proofpoint-ORIG-GUID: CL5xb0cttaozS9hlBWyRob2q_BkQTay2 X-Authority-Analysis: v=2.4 cv=SNNCVPvH c=1 sm=1 tr=0 ts=68af73d0 cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=2OwXVqhp2XgA:10 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=Z7V3-7iYKtOFoFvQ_6sA:9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-27_04,2025-08-26_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 adultscore=0 bulkscore=0 phishscore=0 clxscore=1011 impostorscore=0 malwarescore=0 suspectscore=0 priorityscore=1501 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2507300000 definitions=main-2508230021 Content-Type: text/plain; charset="utf-8" zpci_get_iommu_ctrs() returns counter information to be reported as part of device statistics; these counters are stored as part of the s390_domain. The problem, however, is that the identity domain is not backed by an s390_domain and so the conversion via to_s390_domain() yields a bad address that is zero'd initially and read on-demand later via a sysfs read. These counters aren't necessary for the identity domain; just return NULL in this case. This issue was discovered via KASAN with reports that look like: BUG: KASAN: global-out-of-bounds in zpci_fmb_enable_device when using the identity domain for a device on s390. Cc: stable@vger.kernel.org Fixes: 64af12c6ec3a ("iommu/s390: implement iommu passthrough via identity = domain") Reported-by: Cam Miller Signed-off-by: Matthew Rosato Reviewed-by: Farhan Ali Reviewed-by: Niklas Schnelle Tested-by: Cam Miller --- drivers/iommu/s390-iommu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c index 9c80d61deb2c..d7370347c910 100644 --- a/drivers/iommu/s390-iommu.c +++ b/drivers/iommu/s390-iommu.c @@ -1032,7 +1032,8 @@ struct zpci_iommu_ctrs *zpci_get_iommu_ctrs(struct zp= ci_dev *zdev) =20 lockdep_assert_held(&zdev->dom_lock); =20 - if (zdev->s390_domain->type =3D=3D IOMMU_DOMAIN_BLOCKED) + if (zdev->s390_domain->type =3D=3D IOMMU_DOMAIN_BLOCKED || + zdev->s390_domain->type =3D=3D IOMMU_DOMAIN_IDENTITY) return NULL; =20 s390_domain =3D to_s390_domain(zdev->s390_domain); --=20 2.50.1