From: Matthew Rosato Date: Wed, 27 Aug 2025 21:08:27 +0000 (-0400) Subject: iommu/s390: Fix memory corruption when using identity domain X-Git-Tag: v6.17-rc7~7^2~4 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b3506e9bcc777ed6af2ab631c86a9990ed97b474;p=thirdparty%2Fkernel%2Fstable.git iommu/s390: Fix memory corruption when using identity domain 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 Tested-by: Cam Miller Reviewed-by: Farhan Ali Reviewed-by: Niklas Schnelle Link: https://lore.kernel.org/r/20250827210828.274527-1-mjrosato@linux.ibm.com Signed-off-by: Joerg Roedel --- diff --git a/drivers/iommu/s390-iommu.c b/drivers/iommu/s390-iommu.c index 9c80d61deb2c0..d7370347c9102 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 zpci_dev *zdev) lockdep_assert_held(&zdev->dom_lock); - if (zdev->s390_domain->type == IOMMU_DOMAIN_BLOCKED) + if (zdev->s390_domain->type == IOMMU_DOMAIN_BLOCKED || + zdev->s390_domain->type == IOMMU_DOMAIN_IDENTITY) return NULL; s390_domain = to_s390_domain(zdev->s390_domain);