From: Thomas Gleixner <tglx@linutronix.de>
Date: Mon, 27 Oct 2025 08:43:46 +0000 (+0100)
Subject: x86/uaccess: Use unsafe wrappers for ASM GOTO
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=14219398e3e1ce774d47b2dd55852d9b693cc6e1;p=thirdparty%2Fkernel%2Flinux.git

x86/uaccess: Use unsafe wrappers for ASM GOTO

ASM GOTO is miscompiled by GCC when it is used inside a auto cleanup scope:

bool foo(u32 __user *p, u32 val)
{
	scoped_guard(pagefault)
		unsafe_put_user(val, p, efault);
	return true;
efault:
	return false;
}

It ends up leaking the pagefault disable counter in the fault path. clang
at least fails the build.

Rename unsafe_*_user() to arch_unsafe_*_user() which makes the generic
uaccess header wrap it with a local label that makes both compilers emit
correct code. Same for the kernel_nofault() variants.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://patch.msgid.link/20251027083745.294359925@linutronix.de
---

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 91a3fb8ae7ff4..367297b188c39 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -528,18 +528,18 @@ static __must_check __always_inline bool user_access_begin(const void __user *pt
 #define user_access_save()	smap_save()
 #define user_access_restore(x)	smap_restore(x)
 
-#define unsafe_put_user(x, ptr, label)	\
+#define arch_unsafe_put_user(x, ptr, label)	\
 	__put_user_size((__typeof__(*(ptr)))(x), (ptr), sizeof(*(ptr)), label)
 
 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
-#define unsafe_get_user(x, ptr, err_label)					\
+#define arch_unsafe_get_user(x, ptr, err_label)					\
 do {										\
 	__inttype(*(ptr)) __gu_val;						\
 	__get_user_size(__gu_val, (ptr), sizeof(*(ptr)), err_label);		\
 	(x) = (__force __typeof__(*(ptr)))__gu_val;				\
 } while (0)
 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT
-#define unsafe_get_user(x, ptr, err_label)					\
+#define arch_unsafe_get_user(x, ptr, err_label)					\
 do {										\
 	int __gu_err;								\
 	__inttype(*(ptr)) __gu_val;						\
@@ -618,11 +618,11 @@ do {									\
 } while (0)
 
 #ifdef CONFIG_CC_HAS_ASM_GOTO_OUTPUT
-#define __get_kernel_nofault(dst, src, type, err_label)			\
+#define arch_get_kernel_nofault(dst, src, type, err_label)		\
 	__get_user_size(*((type *)(dst)), (__force type __user *)(src),	\
 			sizeof(type), err_label)
 #else // !CONFIG_CC_HAS_ASM_GOTO_OUTPUT
-#define __get_kernel_nofault(dst, src, type, err_label)			\
+#define arch_get_kernel_nofault(dst, src, type, err_label)			\
 do {									\
 	int __kr_err;							\
 									\
@@ -633,7 +633,7 @@ do {									\
 } while (0)
 #endif // CONFIG_CC_HAS_ASM_GOTO_OUTPUT
 
-#define __put_kernel_nofault(dst, src, type, err_label)			\
+#define arch_put_kernel_nofault(dst, src, type, err_label)		\
 	__put_user_size(*((type *)(src)), (__force type __user *)(dst),	\
 			sizeof(type), err_label)