From: Christophe Leroy christophe.leroy@csgroup.eu
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@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... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/misc/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- 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)