[Intel-gfx] [PATCH v2] iommu/vt-d: fix overflow of iommu->domains array

[Jan Niehusmann]

The valid range of 'did' in get_iommu_domain(*iommu, did)
is 0..cap_ndoms(iommu->cap), so don't exceed that
range in free_all_cpu_cached_iovas().

The user-visible impact of the out-of-bounds access is the machine
hanging on suspend-to-ram. It is, in fact, a kernel panic, but due
to already suspended devices, that's often not visible to the user.

Fixes: 22e2f9fa63b0 ("iommu/vt-d: Use per-cpu IOVA caching")
Signed-off-by: Jan Niehusmann <jan at gondor.com>
Tested-By: Marius Vlad <marius.c.vlad at intel.com>
---
Added some details and Tested-By to the commit message. Patch is unchanged.

Posted to intel-gfx at lists.freedesktop.org and iommu at lists.linux-foundation.org
where the issue was discussed.

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index a644d0c..82989d4 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4600,7 +4600,7 @@ static void free_all_cpu_cached_iovas(unsigned int cpu)
 		if (!iommu)
 			continue;
 
-		for (did = 0; did < 0xffff; did++) {
+		for (did = 0; did < cap_ndoms(iommu->cap); did++) {
 			domain = get_iommu_domain(iommu, did);
 
 			if (!domain)
-- 
2.1.4