6.16-stable review patch. If anyone has any objections, please let me know.
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From: Matthew Rosato mjrosato@linux.ibm.com
commit b3506e9bcc777ed6af2ab631c86a9990ed97b474 upstream.
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 cam@linux.ibm.com Signed-off-by: Matthew Rosato mjrosato@linux.ibm.com Tested-by: Cam Miller cam@linux.ibm.com Reviewed-by: Farhan Ali alifm@linux.ibm.com Reviewed-by: Niklas Schnelle schnelle@linux.ibm.com Link: https://lore.kernel.org/r/20250827210828.274527-1-mjrosato@linux.ibm.com Signed-off-by: Joerg Roedel joerg.roedel@amd.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/iommu/s390-iommu.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/iommu/s390-iommu.c +++ b/drivers/iommu/s390-iommu.c @@ -1031,7 +1031,8 @@ struct zpci_iommu_ctrs *zpci_get_iommu_c
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);