This is backport for 4.14

(cherry picked from commit bc93a22a19eb2b68a16ecf04cdf4b2ed65aaf398)

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... --- drivers/misc/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile index 76f6a4f628b3..cc0df7280fe5 100644 --- a/drivers/misc/Makefile +++ b/drivers/misc/Makefile @@ -69,7 +69,7 @@ KCOV_INSTRUMENT_lkdtm_rodata.o := n

OBJCOPYFLAGS := OBJCOPYFLAGS_lkdtm_rodata_objcopy.o := \ - --rename-section .text=.rodata,alloc,readonly,load + --rename-section .text=.rodata,alloc,readonly,load,contents targets += lkdtm_rodata.o lkdtm_rodata_objcopy.o $(obj)/lkdtm_rodata_objcopy.o: $(obj)/lkdtm_rodata.o FORCE $(call if_changed,objcopy)