[Maverick] request: CONFIG_DEBUG_STRICT_USER_COPY_CHECKS

[Leann Ogasawara]

On Thu, 2010-07-15 at 15:35 -0700, Kees Cook wrote:
> Hi!

Hi Kees,

> Could we enable this test, just to be safer during compiles? It won't
> affect run-time, it just forces the build to be safer, IIUC:

I wouldn't be opposed to enabling this, but at the moment doing so
results in build failures.  If you have time, care to send a patch to
fix up this build failures?  Otherwise, can you file a bug for us to
track this request.

Thanks,
Leann

> arch/x86/include/asm/uaccess_32.h:
> 
> extern void copy_from_user_overflow(void)
> #ifdef CONFIG_DEBUG_STRICT_USER_COPY_CHECKS
>         __compiletime_error("copy_from_user() buffer size is not provably correct")
> #else
>         __compiletime_warning("copy_from_user() buffer size is not provably correct")
> #endif
> 
> static inline unsigned long __must_check copy_from_user(void *to,
>                                           const void __user *from,
>                                           unsigned long n)
> {
>         int sz = __compiletime_object_size(to);
> 
>         if (likely(sz == -1 || sz >= n))
>                 n = _copy_from_user(to, from, n);
>         else
>                 copy_from_user_overflow();
> 
>         return n;
> }
> 
> 
> -- 
> Kees Cook
> Ubuntu Security Team
>