Commit b3506e9b authored by Matthew Rosato's avatar Matthew Rosato Committed by Joerg Roedel
Browse files

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: 64af12c6 ("iommu/s390: implement iommu passthrough via identity domain")
Reported-by: default avatarCam Miller <cam@linux.ibm.com>
Signed-off-by: default avatarMatthew Rosato <mjrosato@linux.ibm.com>
Tested-by: default avatarCam Miller <cam@linux.ibm.com>
Reviewed-by: default avatarFarhan Ali <alifm@linux.ibm.com>
Reviewed-by: default avatarNiklas Schnelle <schnelle@linux.ibm.com>
Link: https://lore.kernel.org/r/20250827210828.274527-1-mjrosato@linux.ibm.com


Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
parent 923b7058

drivers/iommu/s390-iommu.c

+2 −1
Original line number Diff line number Diff line
@@ -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);