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 --- 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)