From 2c8340eda45cee1784f7b29e6d7dcc740ea3d02a Mon Sep 17 00:00:00 2001
From: Rik van Riel <riel@redhat.com>
Date: Wed, 12 Jul 2017 14:36:29 -0700
Subject: [PATCH] sh64: ascii armor the sh64 boot init stack canary

Use the ascii-armor canary to prevent unterminated C string overflows
from being able to successfully overwrite the canary, even if they
somehow obtain the canary value.

Inspired by execshield ascii-armor and Daniel Micay's linux-hardened
tree.

Link: http://lkml.kernel.org/r/20170524123446.78510066@annuminas.surriel.com
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 arch/sh/include/asm/stackprotector.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/sh/include/asm/stackprotector.h b/arch/sh/include/asm/stackprotector.h
index d9df3a76847c3..141515a43b781 100644
--- a/arch/sh/include/asm/stackprotector.h
+++ b/arch/sh/include/asm/stackprotector.h
@@ -19,6 +19,7 @@ static __always_inline void boot_init_stack_canary(void)
 	/* Try to get a semi random initial value. */
 	get_random_bytes(&canary, sizeof(canary));
 	canary ^= LINUX_VERSION_CODE;
+	canary &= CANARY_MASK;
 
 	current->stack_canary = canary;
 	__stack_chk_guard = current->stack_canary;
-- 
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