Re: [PATCH] iommu: Use correctly sized arguments for bit field

[Joerg Roedel]

On Wed, Dec 15, 2021 at 03:24:32PM -0800, Kees Cook wrote:
> The find.h APIs are designed to be used only on unsigned long arguments.
> This can technically result in a over-read, but it is harmless in this
> case. Regardless, fix it to avoid the warning seen under -Warray-bounds,
> which we'd like to enable globally:
> 
> In file included from ./include/linux/bitmap.h:9,
>                  from drivers/iommu/intel/iommu.c:17:
> drivers/iommu/intel/iommu.c: In function 'domain_context_mapping_one':
> ./include/linux/find.h:119:37: warning: array subscript 'long unsigned int[0]' is partly outside array bounds of 'int[1]' [-Warray-bounds]
>   119 |                 unsigned long val = *addr & GENMASK(size - 1, 0);
>       |                                     ^~~~~
> drivers/iommu/intel/iommu.c:2115:18: note: while referencing 'max_pde'
>  2115 |         int pds, max_pde;
>       |                  ^~~~~~~
> 
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
>  drivers/iommu/intel/iommu.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Applied, thanks.