Tested-by: Cam Miller cam@linux.ibm.com
On 8/27/25 17:08, Matthew Rosato wrote:
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
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 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)s390_domain = to_s390_domain(zdev->s390_domain);