[PATCH 5/5] sh64: ascii armor the sh64 boot init stack canary

[Rik van Riel]

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.

Signed-off-by: Rik van Riel <r...@redhat.com>
---
 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 d9df3a76847c..141515a43b78 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;