The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From bc93a22a19eb2b68a16ecf04cdf4b2ed65aaf398 Mon Sep 17 00:00:00 2001 From: Christophe Leroy christophe.leroy@csgroup.eu Date: Fri, 8 Oct 2021 18:58:40 +0200 Subject: [PATCH] lkdtm: Fix content of section containing lkdtm_rodata_do_nothing()

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") Cc: stable@vger.kernel.org Cc: Kees Cook keescook@chromium.org 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 christophe.leroy@csgroup.eu Reviewed-by: Nick Desaulniers ndesaulniers@google.com Signed-off-by: Kees Cook keescook@chromium.org Link: https://lore.kernel.org/r/8900731fbc05fb8b0de18af7133a8fc07c3c53a1.163371217...

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)