From: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Thu, 8 Feb 2018 17:09:26 -0600
Subject: x86/debug, objtool: Annotate WARN()-related UD2 as reachable
Git-commit: 2b5db66862b95532cb6cca8165ae6eb73633cf85
Patch-mainline: v4.16-rc2
References: bsc#1068032 CVE-2017-5754
By default, objtool assumes that a UD2 is a dead end. This is mainly
because GCC 7+ sometimes inserts a UD2 when it detects a divide-by-zero
condition.
Now that WARN() is moving back to UD2, annotate the code after it as
reachable so objtool can follow the code flow.
Reported-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kbuild test robot <fengguang.wu@intel.com>
Link: http://lkml.kernel.org/r/0e483379275a42626ba8898117f918e1bf661e40.1518130694.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Borislav Petkov <bp@suse.de>
---
arch/x86/include/asm/bug.h | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/bug.h b/arch/x86/include/asm/bug.h
index 34d99af43994..71e6f4bf9161 100644
--- a/arch/x86/include/asm/bug.h
+++ b/arch/x86/include/asm/bug.h
@@ -77,7 +77,11 @@ do { \
unreachable(); \
} while (0)
-#define __WARN_FLAGS(flags) _BUG_FLAGS(ASM_UD0, BUGFLAG_WARNING|(flags))
+#define __WARN_FLAGS(flags) \
+do { \
+ _BUG_FLAGS(ASM_UD0, BUGFLAG_WARNING|(flags)); \
+ annotate_reachable(); \
+} while (0)
#include <asm-generic/bug.h>