From: Kristina Martsenko <kristina.martsenko@xxxxxxx>
[ Upstream commit f68022ae0aeb0803450e05abc0e984027c33ef1b ]
The CFI test uses the branch-protection=none compiler attribute to
disable PAC return address protection on a function. While newer GCC
versions support this attribute, older versions (GCC 7 and 8) instead
supported the sign-return-address=none attribute, leading to a build
failure when the test is built with older compilers. Fix it by checking
which attribute is supported and using the correct one.
Fixes: 2e53b877dc12 ("lkdtm: Add CFI_BACKWARD to test ROP mitigations")
Reported-by: Daniel Díaz <daniel.diaz@xxxxxxxxxx>
Signed-off-by: Kristina Martsenko <kristina.martsenko@xxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Link: https://lore.kernel.org/all/CAEUSe78kDPxQmQqCWW-_9LCgJDFhAeMoVBFnX9QLx18Z4uT4VQ@xxxxxxxxxxxxxx/
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
drivers/misc/lkdtm/cfi.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/misc/lkdtm/cfi.c b/drivers/misc/lkdtm/cfi.c
index 71483cb1e422..f4fd30f7a9a0 100644
--- a/drivers/misc/lkdtm/cfi.c
+++ b/drivers/misc/lkdtm/cfi.c
@@ -51,7 +51,11 @@ static void lkdtm_CFI_FORWARD_PROTO(void)
# ifdef CONFIG_ARM64_BTI_KERNEL
# define __no_pac "branch-protection=bti"
# else
-# define __no_pac "branch-protection=none"
+# ifdef CONFIG_CC_HAS_BRANCH_PROT_PAC_RET
+# define __no_pac "branch-protection=none"
+# else
+# define __no_pac "sign-return-address=none"
+# endif
# endif
# define __no_ret_protection __noscs __attribute__((__target__(__no_pac)))
#else
--
2.35.1
