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

[Vasileios Almpanis]

Reviewed-by: Vasileios Almpanis <vasileios.almpanis at virtuozzo.com>

On 3/23/26 9:31 PM, Konstantin Khorenko wrote:
>    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;