[PATCH 4.19 05/58] efi/libstub: Disable Shadow Call Stack

[Greg Kroah-Hartman]

From: Sami Tolvanen <samitolvanen@xxxxxxxxxx>

[ Upstream commit cc49c71d2abe99c1c2c9bedf0693ad2d3ee4a067 ]

Shadow stacks are not available in the EFI stub, filter out SCS flags.

Suggested-by: James Morse <james.morse@xxxxxxx>
Signed-off-by: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
Stable-dep-of: 1a3887924a7e ("efi: libstub: Disable struct randomization")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/firmware/efi/libstub/Makefile | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index d3777d754984..e0cff3b942ac 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -31,6 +31,9 @@ KBUILD_CFLAGS			:= $(cflags-y) -DDISABLE_BRANCH_PROFILING \
 				   $(call cc-option,-fno-addrsig) \
 				   -D__DISABLE_EXPORTS
 
+# remove SCS flags from all objects in this directory
+KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_SCS), $(KBUILD_CFLAGS))
+
 GCOV_PROFILE			:= n
 KASAN_SANITIZE			:= n
 UBSAN_SANITIZE			:= n
-- 
2.35.1