Messages in this thread Patch in this message | | | From | Kees Cook <> | Subject | [PATCH] lkdtm: Disable CFI checking for perms functions | Date | Tue, 30 Apr 2024 16:49:57 -0700 |
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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 --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; -- 2.34.1
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