linux-kernel - [PATCH 4.4 64/75] ARM: 8795/1: spectre-v1.1: use put_user() for __put

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Message-Id: <20191108174805.004326669@linuxfoundation.org>
Date:   Fri,  8 Nov 2019 19:50:21 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Julien Thierry <julien.thierry@....com>,
        Russell King <rmk+kernel@...linux.org.uk>,
        "David A. Long" <dave.long@...aro.org>,
        Sasha Levin <sashal@...nel.org>,
        Ard Biesheuvel <ardb@...nel.org>
Subject: [PATCH 4.4 64/75] ARM: 8795/1: spectre-v1.1: use put_user() for __put_user()

From: Julien Thierry <julien.thierry@....com>

Commit e3aa6243434fd9a82e84bb79ab1abd14f2d9a5a7 upstream.

When Spectre mitigation is required, __put_user() needs to include
check_uaccess. This is already the case for put_user(), so just make
__put_user() an alias of put_user().

Signed-off-by: Julien Thierry <julien.thierry@....com>
Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
Signed-off-by: David A. Long <dave.long@...aro.org>
Reviewed-by: Julien Thierry <julien.thierry@....com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/arm/include/asm/uaccess.h |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--- a/arch/arm/include/asm/uaccess.h
+++ b/arch/arm/include/asm/uaccess.h
@@ -408,6 +408,14 @@ do {									\
 	__pu_err;							\
 })
 
+#ifdef CONFIG_CPU_SPECTRE
+/*
+ * When mitigating Spectre variant 1.1, all accessors need to include
+ * verification of the address space.
+ */
+#define __put_user(x, ptr) put_user(x, ptr)
+
+#else
 #define __put_user(x, ptr)						\
 ({									\
 	long __pu_err = 0;						\
@@ -415,12 +423,6 @@ do {									\
 	__pu_err;							\
 })
 
-#define __put_user_error(x, ptr, err)					\
-({									\
-	__put_user_switch((x), (ptr), (err), __put_user_nocheck);	\
-	(void) 0;							\
-})
-
 #define __put_user_nocheck(x, __pu_ptr, __err, __size)			\
 	do {								\
 		unsigned long __pu_addr = (unsigned long)__pu_ptr;	\
@@ -500,6 +502,7 @@ do {									\
 	: "r" (x), "i" (-EFAULT)				\
 	: "cc")
 
+#endif /* !CONFIG_CPU_SPECTRE */
 
 #ifdef CONFIG_MMU
 extern unsigned long __must_check