From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
commit bc93a22a19eb2b68a16ecf04cdf4b2ed65aaf398 upstream.
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@xxxxxxxxxxxxxxx
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Nathan Chancellor <nathan@xxxxxxxxxx>
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/8900731fbc05fb8b0de18af7133a8fc07c3c53a1.1633712176.git.christophe.leroy@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/misc/lkdtm/Makefile | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/misc/lkdtm/Makefile
+++ b/drivers/misc/lkdtm/Makefile
@@ -13,7 +13,7 @@ KCOV_INSTRUMENT_rodata.o := n
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)
