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 <[email protected]>
> Link: https://lore.kernel.org/r/[email protected]
> Signed-off-by: Ricardo Ribalda <[email protected]>
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
>
