linux-kernel - [PATCH v4 07/15] lkdtm: Disable UNSET

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Message-Id: <20210930180531.1190642-8-samitolvanen@google.com>
Date:   Thu, 30 Sep 2021 11:05:23 -0700
From:   Sami Tolvanen <samitolvanen@...gle.com>
To:     x86@...nel.org
Cc:     Kees Cook <keescook@...omium.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Sedat Dilek <sedat.dilek@...il.com>,
        linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, Sami Tolvanen <samitolvanen@...gle.com>
Subject: [PATCH v4 07/15] lkdtm: Disable UNSET_SMEP with CFI

Disable the UNSET_SMEP test when CONFIG_CFI_CLANG is enabled as
jumping to a call gadget would always trip CFI instead.

Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
Acked-by: Kees Cook <keescook@...omium.org>
---
 drivers/misc/lkdtm/bugs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index 4282b625200f..6e8677852262 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -367,7 +367,7 @@ void lkdtm_STACK_GUARD_PAGE_TRAILING(void)
 
 void lkdtm_UNSET_SMEP(void)
 {
-#if IS_ENABLED(CONFIG_X86_64) && !IS_ENABLED(CONFIG_UML)
+#if IS_ENABLED(CONFIG_X86_64) && !IS_ENABLED(CONFIG_UML) && !IS_ENABLED(CONFIG_CFI_CLANG)
 #define MOV_CR4_DEPTH	64
 	void (*direct_write_cr4)(unsigned long val);
 	unsigned char *insn;
-- 
2.33.0.800.g4c38ced690-goog