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

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Message-ID: <163907981387.23020.13292835544312035646.tip-bot2@tip-bot2>
Date:   Thu, 09 Dec 2021 19:56:53 -0000
From:   "tip-bot2 for Kees Cook" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     stable@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>, 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:     f529cc537b8e907c25f29eb00f50979e8e532cbc
Gitweb:        https://git.kernel.org/tip/f529cc537b8e907c25f29eb00f50979e8e532cbc
Author:        Kees Cook <keescook@...omium.org>
AuthorDate:    Wed, 08 Dec 2021 20:34:56 -08:00
Committer:     Dave Hansen <dave.hansen@...ux.intel.com>
CommitterDate: Thu, 09 Dec 2021 11:48:18 -08:00

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__; \
      |                       ^~~~~~

Cc: stable@...r.kernel.org
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>
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;							\