Re: [PATCH v26 6/9] x86/vdso: Insert endbr32/endbr64 to vDSO
From: Kees Cook <hidden>
Date: 2021-04-28 20:33:13
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On Tue, Apr 27, 2021 at 01:47:17PM -0700, Yu-cheng Yu wrote:
From: "H.J. Lu" <redacted> When Indirect Branch Tracking (IBT) is enabled, vDSO functions may be called indirectly, and must have ENDBR32 or ENDBR64 as the first instruction. The compiler must support -fcf-protection=branch so that it can be used to compile vDSO.
If you respin this, you can maybe rephrase this since CONFIG_X86_IBT has already tested for the compiler support.
Signed-off-by: H.J. Lu <redacted> Signed-off-by: Yu-cheng Yu <redacted> Cc: Andy Lutomirski <luto@kernel.org> Cc: Kees Cook <redacted>
Reviewed-by: Kees Cook <redacted> -Kees
quoted hunk ↗ jump to hunk
--- v24: - Replace CONFIG_X86_CET with CONFIG_X86_IBT to reflect splitting of shadow stack and ibt. arch/x86/entry/vdso/Makefile | 4 ++++ 1 file changed, 4 insertions(+)diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile index 05c4abc2fdfd..a773a5f03b63 100644 --- a/arch/x86/entry/vdso/Makefile +++ b/arch/x86/entry/vdso/Makefile@@ -93,6 +93,10 @@ endif $(vobjs): KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL) +ifdef CONFIG_X86_IBT +$(vobjs) $(vobjs32): KBUILD_CFLAGS += -fcf-protection=branch +endif + # # vDSO code runs in userspace and -pg doesn't help with profiling anyway. #-- 2.21.0
-- Kees Cook