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lkdtm: Disable CFI checking for perms functions

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[ Upstream commit fb28a8862dc4b5bf8e44578338f35d9c6c68339d ]

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()")
Link: https://lore.kernel.org/r/20240430234953.work.760-kees@kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Kees Cook 2024-04-30 16:49:57 -07:00 committed by Greg Kroah-Hartman
parent fbadcde157
commit 1fc82121d0
2 changed files with 2 additions and 2 deletions
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2
drivers/misc/lkdtm/Makefile
View File

@ -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 := \

2
drivers/misc/lkdtm/perms.c
View File

@ -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;