diff mbox series

[v24,8/9] x86/vdso/32: Add ENDBR to __kernel_vsyscall entry point

Message ID 20210401221403.32253-9-yu-cheng.yu@intel.com (mailing list archive)
State New, archived
Headers show
Series Control-flow Enforcement: Indirect Branch Tracking | expand

Commit Message

Yu-cheng Yu April 1, 2021, 10:14 p.m. UTC 
From: "H.J. Lu" <hjl.tools@gmail.com>

ENDBR is a special new instruction for the Indirect Branch Tracking (IBT)
component of CET.  IBT prevents attacks by ensuring that (most) indirect
branches and function calls may only land at ENDBR instructions.  Branches
that don't follow the rules will result in control flow (#CF) exceptions.

ENDBR is a noop when IBT is unsupported or disabled.  Most ENDBR
instructions are inserted automatically by the compiler, but branch
targets written in assembly must have ENDBR added manually.

Add that to __kernel_vsyscall entry point.

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
---
 arch/x86/entry/vdso/vdso32/system_call.S | 2 ++
 1 file changed, 2 insertions(+)
diff mbox series

Patch

diff --git a/arch/x86/entry/vdso/vdso32/system_call.S b/arch/x86/entry/vdso/vdso32/system_call.S
index de1fff7188aa..c962e7e4f7e3 100644
--- a/arch/x86/entry/vdso/vdso32/system_call.S
+++ b/arch/x86/entry/vdso/vdso32/system_call.S
@@ -7,6 +7,7 @@ 
 #include <asm/dwarf2.h>
 #include <asm/cpufeatures.h>
 #include <asm/alternative-asm.h>
+#include <asm/vdso.h>
 
 	.text
 	.globl __kernel_vsyscall
@@ -14,6 +15,7 @@ 
 	ALIGN
 __kernel_vsyscall:
 	CFI_STARTPROC
+	ENDBR
 	/*
 	 * Reshuffle regs so that all of any of the entry instructions
 	 * will preserve enough state.