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| author | Nick Desaulniers <ndesaulniers@google.com> | 2022-08-11 01:24:41 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-08-25 12:17:17 +0300 |
| commit | 013acaa597525b66b67e5fcfbd071b9772d6e53c (patch) | |
| tree | ad7a5ea41af8deb4726f3e585b91391d2766b305 /arch/x86/boot/compressed | |
| parent | 635e8e6f6837130c0ddac25a145f3cd29301c8a3 (diff) | |
| download | linux-013acaa597525b66b67e5fcfbd071b9772d6e53c.tar.xz | |
x86: link vdso and boot with -z noexecstack --no-warn-rwx-segments
commit ffcf9c5700e49c0aee42dcba9a12ba21338e8136 upstream.
Users of GNU ld (BFD) from binutils 2.39+ will observe multiple
instances of a new warning when linking kernels in the form:
ld: warning: arch/x86/boot/pmjump.o: missing .note.GNU-stack section implies executable stack
ld: NOTE: This behaviour is deprecated and will be removed in a future version of the linker
ld: warning: arch/x86/boot/compressed/vmlinux has a LOAD segment with RWX permissions
Generally, we would like to avoid the stack being executable. Because
there could be a need for the stack to be executable, assembler sources
have to opt-in to this security feature via explicit creation of the
.note.GNU-stack feature (which compilers create by default) or command
line flag --noexecstack. Or we can simply tell the linker the
production of such sections is irrelevant and to link the stack as
--noexecstack.
LLVM's LLD linker defaults to -z noexecstack, so this flag isn't
strictly necessary when linking with LLD, only BFD, but it doesn't hurt
to be explicit here for all linkers IMO. --no-warn-rwx-segments is
currently BFD specific and only available in the current latest release,
so it's wrapped in an ld-option check.
While the kernel makes extensive usage of ELF sections, it doesn't use
permissions from ELF segments.
Link: https://lore.kernel.org/linux-block/3af4127a-f453-4cf7-f133-a181cce06f73@kernel.dk/
Link: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ba951afb99912da01a6e8434126b8fac7aa75107
Link: https://github.com/llvm/llvm-project/issues/57009
Reported-and-tested-by: Jens Axboe <axboe@kernel.dk>
Suggested-by: Fangrui Song <maskray@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/boot/compressed')
| -rw-r--r-- | arch/x86/boot/compressed/Makefile | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 292b5bc6e3a3..edfb1a718510 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -57,6 +57,10 @@ else KBUILD_LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \ && echo "-z noreloc-overflow -pie --no-dynamic-linker") endif + +KBUILD_LDFLAGS += -z noexecstack +KBUILD_LDFLAGS += $(call ld-option,--no-warn-rwx-segments) + LDFLAGS_vmlinux := -T hostprogs-y := mkpiggy |