Commit f68022ae authored by Kristina Martsenko's avatar Kristina Martsenko Committed by Kees Cook
Browse files

lkdtm: cfi: Make PAC test work with GCC 7 and 8 



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: 2e53b877 ("lkdtm: Add CFI_BACKWARD to test ROP mitigations")
Reported-by: default avatarDaniel Díaz <daniel.diaz@linaro.org>
Signed-off-by: default avatarKristina Martsenko <kristina.martsenko@arm.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/all/CAEUSe78kDPxQmQqCWW-_9LCgJDFhAeMoVBFnX9QLx18Z4uT4VQ@mail.gmail.com/
parent 00dd027f

drivers/misc/lkdtm/cfi.c

+5 −1
Original line number Original line Diff line number Diff line
@@ -54,7 +54,11 @@ static void lkdtm_CFI_FORWARD_PROTO(void) 
# ifdef CONFIG_ARM64_BTI_KERNEL

# ifdef CONFIG_ARM64_BTI_KERNEL

#  define __no_pac             "branch-protection=bti"

#  define __no_pac             "branch-protection=bti"

# else

# else

#  ifdef CONFIG_CC_HAS_BRANCH_PROT_PAC_RET

#   define __no_pac            "branch-protection=none"

#   define __no_pac            "branch-protection=none"

#  else

#   define __no_pac            "sign-return-address=none"

#  endif

# endif

# endif

# define __no_ret_protection   __noscs __attribute__((__target__(__no_pac)))

# define __no_ret_protection   __noscs __attribute__((__target__(__no_pac)))

#else

#else