On 4/28/2021 1:33 PM, Kees Cook wrote:
On Tue, Apr 27, 2021 at 01:47:17PM -0700, Yu-cheng Yu wrote:
From: "H.J. Lu" <hjl.tools@xxxxxxxxx>
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.
Yes, I will fix this. Thanks for reviewing!
Yu-cheng
Signed-off-by: H.J. Lu <hjl.tools@xxxxxxxxx>
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
-Kees
---
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
