This is a note to let you know that I've just added the patch titled
lkdtm: cfi: Make PAC test work with GCC 7 and 8
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
lkdtm-cfi-make-pac-test-work-with-gcc-7-and-8.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit ddb83fe757780cd35c6a9156fc1ed715862a4c67
Author: Kristina Martsenko <kristina.martsenko@xxxxxxx>
Date: Fri Dec 9 17:34:41 2022 +0000
lkdtm: cfi: Make PAC test work with GCC 7 and 8
[ 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>
diff --git a/drivers/misc/lkdtm/cfi.c b/drivers/misc/lkdtm/cfi.c
index 5245cf6013c9..fc28714ae3a6 100644
--- a/drivers/misc/lkdtm/cfi.c
+++ b/drivers/misc/lkdtm/cfi.c
@@ -54,7 +54,11 @@ 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
