Re: [PATCH v5 12/14] arm64: vdso: disable Shadow Call Stack
From: Mark Rutland <mark.rutland@arm.com>
Date: 2019-11-15 14:44:05
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On Tue, Nov 05, 2019 at 03:56:06PM -0800, Sami Tolvanen wrote:
Shadow stacks are only available in the kernel, so disable SCS instrumentation for the vDSO. Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Reviewed-by: Nick Desaulniers <redacted> Reviewed-by: Kees Cook <redacted>
I gave this a spin, looked at objdump, and found everything in the vDSO was a leaf function. I hacked the code around a bit to force a function call, and I see that just uses x29 and x30 as expected, with nothing touching x18. Reviewed-by: Mark Rutland <mark.rutland@arm.com> Mark.
quoted hunk ↗ jump to hunk
--- arch/arm64/kernel/vdso/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/arch/arm64/kernel/vdso/Makefile b/arch/arm64/kernel/vdso/Makefile index dd2514bb1511..a87a4f11724e 100644 --- a/arch/arm64/kernel/vdso/Makefile +++ b/arch/arm64/kernel/vdso/Makefile@@ -25,7 +25,7 @@ ccflags-y += -DDISABLE_BRANCH_PROFILING VDSO_LDFLAGS := -Bsymbolic -CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os +CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE) -Os $(CC_FLAGS_SCS) KBUILD_CFLAGS += $(DISABLE_LTO) KASAN_SANITIZE := n UBSAN_SANITIZE := n-- 2.24.0.rc1.363.gb1bccd3e3d-goog
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