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From: Ricardo Ribalda <ribalda@chromium.org>
To: "Paul E. McKenney" <paulmck@kernel.org>,
	 Frederic Weisbecker <frederic@kernel.org>,
	 Neeraj Upadhyay <neeraj.upadhyay@kernel.org>,
	 Joel Fernandes <joelagnelf@nvidia.com>,
	 Josh Triplett <josh@joshtriplett.org>,
	Boqun Feng <boqun@kernel.org>,
	 Uladzislau Rezki <urezki@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	 Lai Jiangshan <jiangshanlai@gmail.com>,
	Zqiang <qiang.zhang@linux.dev>,
	 Thomas Gleixner <tglx@kernel.org>,
	Ingo Molnar <mingo@redhat.com>,  Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	 x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	 Chris Li <sparse@chrisli.org>, Dan Carpenter <error27@gmail.com>
Cc: David Laight <david.laight.linux@gmail.com>,
	rcu@vger.kernel.org,  linux-kernel@vger.kernel.org,
	linux-sparse@vger.kernel.org,
	 Ricardo Ribalda <ribalda@chromium.org>
Subject: [PATCH v2 2/2] x86/uaccess: Drop the address space qualifier from put_user()
Date: Mon, 14 Sep 2026 13:53:32 +0000	[thread overview]
Message-ID: <20260914-unqual-v2-2-60a1407a0cd4@chromium.org> (raw)
In-Reply-To: <20260914-unqual-v2-0-60a1407a0cd4@chromium.org>

__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@linaro.org>
Link: https://lore.kernel.org/r/20260825-unqual-v1-2-7024fb81b4f9@chromium.org
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
---
 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


  parent reply	other threads:[~2026-09-14 13:53 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-09-14 13:53 [PATCH v2 0/2] Fix warnings with recent smatch Ricardo Ribalda
2026-09-14 13:53 ` [PATCH v2 1/2] rcu: Drop the address space qualifier from the dereference macros Ricardo Ribalda
2026-09-14 13:53 ` Ricardo Ribalda [this message]
2026-09-14 14:58   ` [PATCH v2 2/2] x86/uaccess: Drop the address space qualifier from put_user() Paul E. McKenney
2026-09-14 15:13     ` Paul E. McKenney
2026-09-23 11:08   ` Ricardo Ribalda
2026-09-23 15:22     ` David Laight
2026-09-24  7:19       ` Ricardo Ribalda
2026-09-24  8:10         ` David Laight
2026-09-24  8:14           ` Ricardo Ribalda

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