The get_hw_info uses a smaller user buffer on purpose to check how
the kernel updates only the fields that fit in the buffer. The test
created a custom smaller struct for this, but the helper function later
treats the buffer as struct iommu_test_hw_info. This makes the compiler
warn about a possible out-of-bounds access (-Warray-bounds).

This keeps the test behavior the same and removes the warning.

Signed-off-by: Kathara Sasikumar <katharasasikumar007@gmail.com>
---
 tools/testing/selftests/iommu/iommufd.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/tools/testing/selftests/iommu/iommufd.c b/tools/testing/selftests/iommu/iommufd.c
index 10e051b6f592..f6aceb65313f 100644
--- a/tools/testing/selftests/iommu/iommufd.c
+++ b/tools/testing/selftests/iommu/iommufd.c
@@ -755,9 +755,7 @@ TEST_F(iommufd_ioas, get_hw_info)
 		struct iommu_test_hw_info info;
 		uint64_t trailing_bytes;
 	} buffer_larger;
-	struct iommu_test_hw_info_buffer_smaller {
-		__u32 flags;
-	} buffer_smaller;
+	struct iommu_test_hw_info buffer_smaller;
 
 	if (self->device_id) {
 		uint8_t max_pasid = 0;
-- 
2.51.0

On Wed, Dec 10, 2025 at 09:13:42PM +0000, Kathara Sasikumar wrote:
> The get_hw_info uses a smaller user buffer on purpose to check how
> the kernel updates only the fields that fit in the buffer. The test
> created a custom smaller struct for this, but the helper function later
> treats the buffer as struct iommu_test_hw_info. This makes the compiler
> warn about a possible out-of-bounds access (-Warray-bounds).
> 
> This keeps the test behavior the same and removes the warning.
> 
> Signed-off-by: Kathara Sasikumar <katharasasikumar007@gmail.com>
> ---
>  tools/testing/selftests/iommu/iommufd.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)

This breaks the test, I already posted a fix, it should be in linux-next.

Jason