Re: [PATCH] lkdtm: cfi: Fix type width for masking PAC bits

[Randy Dunlap]

On 4/26/22 17:12, Kees Cook wrote:
> The masking for PAC bits wasn't handling 32-bit architectures correctly.
> Replace the u64 cast with uintptr_t.
> 
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/lkml/CAMuHMdVz-J-1ZQ08u0bsQihDkcRmEPrtX5B_oRJ+Ns5jrasnUw@xxxxxxxxxxxxxx
> Fixes: 2e53b877dc12 ("lkdtm: Add CFI_BACKWARD to test ROP mitigations")
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

Tested-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
fwiw
Thanks.

> ---
>  drivers/misc/lkdtm/cfi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/lkdtm/cfi.c b/drivers/misc/lkdtm/cfi.c
> index 804965a480b7..666a7f4bc137 100644
> --- a/drivers/misc/lkdtm/cfi.c
> +++ b/drivers/misc/lkdtm/cfi.c
> @@ -59,7 +59,7 @@ static void lkdtm_CFI_FORWARD_PROTO(void)
>  #endif
>  
>  #define no_pac_addr(addr)      \
> -	((__force __typeof__(addr))((__force u64)(addr) | PAGE_OFFSET))
> +	((__force __typeof__(addr))((uintptr_t)(addr) | PAGE_OFFSET))
>  
>  /* The ultimate ROP gadget. */
>  static noinline __no_ret_protection

-- 
~Randy