[PATCH][next] iommu/vt-d: Fix out-bounds-warning in intel_svm_page_response()

Gustavo A. R. Silva
2021-04-13T19:54:15Z

Replace call to memcpy() with just a couple of simple assignments in
order to fix the following out-of-bounds warning:

drivers/iommu/intel/svm.c:1198:4: warning: 'memcpy' offset [25, 32] from the object at 'desc' is out of the bounds of referenced subobject 'qw2' with type 'long long unsigned int' at offset 16 [-Warray-bounds]

The problem is that the original code is trying to copy data into a
couple of struct members adjacent to each other in a single call to
memcpy(). This causes a legitimate compiler warning because memcpy()
overruns the length of &desc.qw2.

This helps with the ongoing efforts to globally enable -Warray-bounds
and get us closer to being able to tighten the FORTIFY_SOURCE routines
on memcpy().

Link: https://github.com/KSPP/linux/issues/109
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
drivers/iommu/intel/svm.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 5165cea90421..65909f504c50 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -1194,9 +1194,10 @@ int intel_svm_page_response(struct device *dev,
desc.qw1 = QI_PGRP_IDX(prm->grpid) | QI_PGRP_LPIG(last_page);
desc.qw2 = 0;
desc.qw3 = 0;
- if (private_present)
- memcpy(&desc.qw2, prm->private_data,
- sizeof(prm->private_data));
+ if (private_present) {
+ desc.qw2 = prm->private_data[0];
+ desc.qw3 = prm->private_data[1];
+ }

qi_submit_sync(iommu, &desc, 1, 0);
}
--
2.27.0