On Fri, Dec 05, 2025 at 08:39:59PM -0400, Jason Gunthorpe wrote:
> GCC gets a bit confused and reports:
>
> In function '_test_cmd_get_hw_info',
> inlined from 'iommufd_ioas_get_hw_info' at iommufd.c:779:3,
> inlined from 'wrapper_iommufd_ioas_get_hw_info' at iommufd.c:752:1:
> >> iommufd_utils.h:804:37: 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=]
> 804 | assert(!info->flags);
> | ~~~~^~~~~~~
> iommufd.c: In function 'wrapper_iommufd_ioas_get_hw_info':
> iommufd.c:761:11: note: object 'buffer_smaller' of size 4
> 761 | } buffer_smaller;
> | ^~~~~~~~~~~~~~
>
> While it is true that "struct iommu_test_hw_info[0]" is partly out of
> bounds of the input pointer, it is not true that info->flags is out of
> bounds. Unclear why it warns on this.
>
> Reuse an existing properly sized stack buffer and pass a truncated length
> instead to test the same thing.
>
> Fixes: af4fde93c319 ("iommufd/selftest: Add coverage for IOMMU_GET_HW_INFO
> ioctl")
> Reported-by: kernel test robot <[email protected]>
> Closes:
> https://lore.kernel.org/oe-kbuild-all/[email protected]/
> Signed-off-by: Jason Gunthorpe <[email protected]>
Reviewed-by: Nicolin Chen <[email protected]>
