Re: [PATCH v2 2/2] x86/uaccess: Drop the address space qualifier from put_user()

[Paul E. McKenney]

On Mon, Sep 14, 2026 at 01:53:32PM +0000, Ricardo Ribalda wrote:
> __typeof__() preserves every qualifier, the address space included.
> 
> When we do __typeof(*__user *int), we are declaring a __user integer,
> which is pretty much meaningless. A value in a register or in the stack
> does not live in the user address space.
> 
> This annotation did not trigger any error until a recent version of
> smatch[1] started caring. And as a result of that now we have tens of
> warnings like:
> 
>   drivers/media/usb/uvc/uvc_v4l2.c:1112:13: warning: incorrect type in argument 2 (different address spaces)
>   drivers/media/usb/uvc/uvc_v4l2.c:1112:13:    expected void const *from
>   drivers/media/usb/uvc/uvc_v4l2.c:1112:13:    got unsigned int __user *
> 
> Instead of __typeof__() use TYPEOF_UNQUAL(). It maps to
> __typeof_unqual__() in recent compilers, so the address space annotation
> is gone.
> 
> [1] https://github.com/error27/smatch/commit/e53027a4e816a772403baafa83c09e4a94c1cb8f
> 
> Suggested-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/20260825-unqual-v1-2-7024fb81b4f9@xxxxxxxxxxxx
> Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>

Queued for testing and review, thank you both!

							Thanx, Paul

> ---
>  arch/x86/include/asm/uaccess.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
> index 3a0dd3c2b233..4e576c0b9131 100644
> --- a/arch/x86/include/asm/uaccess.h
> +++ b/arch/x86/include/asm/uaccess.h
> @@ -172,7 +172,7 @@ extern void __put_user_nocheck_8(void);
>  	int __ret_pu;							\
>  	void __user *__ptr_pu;						\
>  	register __typeof__(*(ptr)) __val_pu asm("%"_ASM_AX);		\
> -	__typeof__(*(ptr)) __x = (x); /* eval x once */			\
> +	TYPEOF_UNQUAL(*(ptr)) __x = (x); /* eval x once */		\
>  	__typeof__(ptr) __ptr = (ptr); /* eval ptr once */		\
>  	__chk_user_ptr(__ptr);						\
>  	__ptr_pu = __ptr;						\
> @@ -231,7 +231,7 @@ extern void __put_user_nocheck_8(void);
>  
>  #define __put_user_size(x, ptr, size, label)				\
>  do {									\
> -	__typeof__(*(ptr)) __x = (x); /* eval x once */			\
> +	TYPEOF_UNQUAL(*(ptr)) __x = (x); /* eval x once */		\
>  	__typeof__(ptr) __ptr = (ptr); /* eval ptr once */		\
>  	__chk_user_ptr(__ptr);						\
>  	switch (size) {							\
> 
> -- 
> 2.55.0.1007.g17ff1f9808-goog
>