Re: [PATCH] lkdtm: Fix content of section containing lkdtm_rodata_do_nothing()
From: Nick Desaulniers <ndesaulniers@google.com>
Date: 2021-10-08 18:13:01
Also in:
lkml, stable
On Fri, Oct 8, 2021 at 9:59 AM Christophe Leroy [off-list ref] wrote:
On a kernel without CONFIG_STRICT_KERNEL_RWX, running EXEC_RODATA
test leads to "Illegal instruction" failure.
Looking at the content of rodata_objcopy.o, we see that the
function content zeroes only:
Disassembly of section .rodata:
0000000000000000 <.lkdtm_rodata_do_nothing>:
0: 00 00 00 00 .long 0x0
Add the contents flag in order to keep the content of the section
while renaming it.
Disassembly of section .rodata:
0000000000000000 <.lkdtm_rodata_do_nothing>:
0: 4e 80 00 20 blr
Fixes: e9e08a07385e ("lkdtm: support llvm-objcopy")Thanks for the patch; sorry I broke this. Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
quoted hunk ↗ jump to hunk
Cc: stable@vger.kernel.org Cc: Kees Cook <redacted> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Nathan Chancellor <nathan@kernel.org> Signed-off-by: Christophe Leroy <redacted> --- drivers/misc/lkdtm/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/drivers/misc/lkdtm/Makefile b/drivers/misc/lkdtm/Makefile index aa12097668d3..e2984ce51fe4 100644 --- a/drivers/misc/lkdtm/Makefile +++ b/drivers/misc/lkdtm/Makefile@@ -20,7 +20,7 @@ CFLAGS_REMOVE_rodata.o += $(CC_FLAGS_LTO) OBJCOPYFLAGS := OBJCOPYFLAGS_rodata_objcopy.o := \ - --rename-section .noinstr.text=.rodata,alloc,readonly,load + --rename-section .noinstr.text=.rodata,alloc,readonly,load,contents targets += rodata.o rodata_objcopy.o $(obj)/rodata_objcopy.o: $(obj)/rodata.o FORCE $(call if_changed,objcopy) --2.31.1
-- Thanks, ~Nick Desaulniers