linux-kernel - [tip: x86/cleanups] x86/uaccess: Move variable into switch case statement

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Message-ID: <163916032315.23020.145458656435254901.tip-bot2@tip-bot2>
Date:   Fri, 10 Dec 2021 18:18:43 -0000
From:   "tip-bot2 for Kees Cook" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Kees Cook <keescook@...omium.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Borislav Petkov <bp@...e.de>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: x86/cleanups] x86/uaccess: Move variable into switch case statement

The following commit has been merged into the x86/cleanups branch of tip:

Commit-ID:     61646ca83d3889696f2772edaff122dd96a2935e
Gitweb:        https://git.kernel.org/tip/61646ca83d3889696f2772edaff122dd96a2935e
Author:        Kees Cook <keescook@...omium.org>
AuthorDate:    Wed, 08 Dec 2021 20:34:56 -08:00
Committer:     Borislav Petkov <bp@...e.de>
CommitterDate: Fri, 10 Dec 2021 19:13:00 +01:00

x86/uaccess: Move variable into switch case statement

When building with automatic stack variable initialization, GCC 12
complains about variables defined outside of switch case statements.
Move the variable into the case that uses it, which silences the warning:

./arch/x86/include/asm/uaccess.h:317:23: warning: statement will never be executed [-Wswitch-unreachable]
  317 |         unsigned char x_u8__; \
      |                       ^~~~~~

Fixes: 865c50e1d279 ("x86/uaccess: utilize CONFIG_CC_HAS_ASM_GOTO_OUTPUT")
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Link: https://lkml.kernel.org/r/20211209043456.1377875-1-keescook@chromium.org
---
 arch/x86/include/asm/uaccess.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 33a6840..8ab9e79 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -314,11 +314,12 @@ do {									\
 do {									\
 	__chk_user_ptr(ptr);						\
 	switch (size) {							\
-	unsigned char x_u8__;						\
-	case 1:								\
+	case 1:	{							\
+		unsigned char x_u8__;					\
 		__get_user_asm(x_u8__, ptr, "b", "=q", label);		\
 		(x) = x_u8__;						\
 		break;							\
+	}								\
 	case 2:								\
 		__get_user_asm(x, ptr, "w", "=r", label);		\
 		break;							\