From: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
commit e9e08a07385e08f1a7f85c5d1e345c21c9564963 upstream.
With CONFIG_LKDTM=y and make OBJCOPY=llvm-objcopy, llvm-objcopy errors:
llvm-objcopy: error: --set-section-flags=.text conflicts with
--rename-section=.text=.rodata
Rather than support setting flags then renaming sections vs renaming
then setting flags, it's simpler to just change both at the same time
via --rename-section. Adding the load flag is required for GNU objcopy
to mark .rodata Type as PROGBITS after the rename.
This can be verified with:
$ readelf -S drivers/misc/lkdtm/rodata_objcopy.o
...
Section Headers:
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
...
[ 1] .rodata PROGBITS 0000000000000000 00000040
0000000000000004 0000000000000000 A 0 0 4
...
Which shows that .text is now renamed .rodata, the alloc flag A is set,
the type is PROGBITS, and the section is not flagged as writeable W.
Cc: stable@xxxxxxxxxxxxxxx
Link: https://sourceware.org/bugzilla/show_bug.cgi?id=24554
Link: https://github.com/ClangBuiltLinux/linux/issues/448
Reported-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
Suggested-by: Alan Modra <amodra@xxxxxxxxx>
Suggested-by: Jordan Rupprect <rupprecht@xxxxxxxxxx>
Suggested-by: Kees Cook <keescook@xxxxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/misc/lkdtm/Makefile | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/misc/lkdtm/Makefile
+++ b/drivers/misc/lkdtm/Makefile
@@ -13,8 +13,7 @@ KCOV_INSTRUMENT_rodata.o := n
OBJCOPYFLAGS :=
OBJCOPYFLAGS_rodata_objcopy.o := \
- --set-section-flags .text=alloc,readonly \
- --rename-section .text=.rodata
+ --rename-section .text=.rodata,alloc,readonly,load
targets += rodata.o rodata_objcopy.o
$(obj)/rodata_objcopy.o: $(obj)/rodata.o FORCE
$(call if_changed,objcopy)
