diff mbox series

lkdtm: Disable CFI checking for perms functions

Message ID 20240430234953.work.760-kees@kernel.org (mailing list archive)
State Mainlined
Commit fb28a8862dc4b5bf8e44578338f35d9c6c68339d
Headers show
Series lkdtm: Disable CFI checking for perms functions | expand

Commit Message

Kees Cook April 30, 2024, 11:49 p.m. UTC
The EXEC_RODATA test plays a lot of tricks to live in the .rodata section,
and once again ran into objtool's (completely reasonable) assumptions
that executable code should live in an executable section. However, this
manifested only under CONFIG_CFI_CLANG=y, as one of the .cfi_sites was
pointing into the .rodata section.

Since we're testing non-CFI execution properties in perms.c (and
rodata.c), we can disable CFI for the involved functions, and remove the
CFI arguments from rodata.c entirely.

Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202308301532.d7acf63e-oliver.sang@intel.com
Fixes: 6342a20efbd8 ("objtool: Add elf_create_section_pair()")
Signed-off-by: Kees Cook <keescook@chromium.org>
---
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
---
 drivers/misc/lkdtm/Makefile | 2 +-
 drivers/misc/lkdtm/perms.c  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile
index 95ef971b5e1c..b28701138b4b 100644
--- a/drivers/misc/lkdtm/Makefile
+++ b/drivers/misc/lkdtm/Makefile
@@ -19,7 +19,7 @@  KASAN_SANITIZE_rodata.o			:= n
 KCSAN_SANITIZE_rodata.o			:= n
 KCOV_INSTRUMENT_rodata.o		:= n
 OBJECT_FILES_NON_STANDARD_rodata.o	:= y
-CFLAGS_REMOVE_rodata.o			+= $(CC_FLAGS_LTO) $(RETHUNK_CFLAGS)
+CFLAGS_REMOVE_rodata.o			+= $(CC_FLAGS_LTO) $(RETHUNK_CFLAGS) $(CC_FLAGS_CFI)
 
 OBJCOPYFLAGS :=
 OBJCOPYFLAGS_rodata_objcopy.o	:= \
diff --git a/drivers/misc/lkdtm/perms.c b/drivers/misc/lkdtm/perms.c
index b93404d65650..5b861dbff27e 100644
--- a/drivers/misc/lkdtm/perms.c
+++ b/drivers/misc/lkdtm/perms.c
@@ -61,7 +61,7 @@  static void *setup_function_descriptor(func_desc_t *fdesc, void *dst)
 	return fdesc;
 }
 
-static noinline void execute_location(void *dst, bool write)
+static noinline __nocfi void execute_location(void *dst, bool write)
 {
 	void (*func)(void);
 	func_desc_t fdesc;