[Devel] [PATCH vz10 05/15] selftests/iommu: suppress -Warray-bounds in _test_cmd_get_hw_info

[Konstantin Khorenko]

  In function '_test_cmd_get_hw_info',
      inlined from 'iommufd_ioas_get_hw_info' at iommufd.c:614:3,
      inlined from 'wrapper_iommufd_ioas_get_hw_info' at iommufd.c:589:1:
  iommufd_utils.h:683:37: warning: array subscript 'struct iommu_test_hw_info[0]' is partly outside array bounds of 'struct iommu_test_hw_info_buffer_smaller[1]' [-Warray-bounds=]
    683 |                         assert(!info->flags);
        |                                 ~~~~^~~~~~~

The test intentionally passes a smaller buffer to exercise the kernel's
handling of undersized user buffers. Runtime data_len checks make the
access safe, but GCC cannot prove this statically. Suppress the warning
locally with a pragma.

https://virtuozzo.atlassian.net/browse/VSTOR-127529
Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>

Feature: fix selftests
---
 tools/testing/selftests/iommu/iommufd_utils.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/testing/selftests/iommu/iommufd_utils.h b/tools/testing/selftests/iommu/iommufd_utils.h
index 40f6f14ce136..1c65c1cde814 100644
--- a/tools/testing/selftests/iommu/iommufd_utils.h
+++ b/tools/testing/selftests/iommu/iommufd_utils.h
@@ -676,12 +676,19 @@ static int _test_cmd_get_hw_info(int fd, __u32 device_id, void *data,
 		}
 	}
 
+	/*
+	 * When data_len is smaller than sizeof(*info), GCC warns about
+	 * out-of-bounds access.  The runtime data_len checks make this safe.
+	 */
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Warray-bounds"
 	if (info) {
 		if (data_len >= offsetofend(struct iommu_test_hw_info, test_reg))
 			assert(info->test_reg == IOMMU_HW_INFO_SELFTEST_REGVAL);
 		if (data_len >= offsetofend(struct iommu_test_hw_info, flags))
 			assert(!info->flags);
 	}
+#pragma GCC diagnostic pop
 
 	if (capabilities)
 		*capabilities = cmd.out_capabilities;
-- 
2.47.1