From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kees Cook Subject: Re: linux-next: build failure after merge of the kspp tree Date: Fri, 27 Jul 2018 09:00:19 -0700 Message-ID: References: <20180727190207.7ce1c9b0@canb.auug.org.au> <20180727190647.3525f5f7@canb.auug.org.au> <20180727205511.7c0f2e62@canb.auug.org.au> <20180727125522.GA6173@arm.com> <20180727130106.GB6173@arm.com> <20180727132742.GB28549@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20180727132742.GB28549@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Will Deacon Cc: Stephen Rothwell , Linux-Next Mailing List , Linux Kernel Mailing List , Alexander Popov , Catalin Marinas , Laura Abbott List-Id: linux-next.vger.kernel.org On Fri, Jul 27, 2018 at 6:27 AM, Will Deacon wrote: > On Fri, Jul 27, 2018 at 02:01:06PM +0100, Will Deacon wrote: >> On Fri, Jul 27, 2018 at 01:55:22PM +0100, Will Deacon wrote: >> > On Fri, Jul 27, 2018 at 08:55:11PM +1000, Stephen Rothwell wrote: >> > > On Fri, 27 Jul 2018 19:06:47 +1000 Stephen Rothwell wrote: >> > > > >> > > > On Fri, 27 Jul 2018 19:02:07 +1000 Stephen Rothwell wrote: >> > > > > >> > > > > After merging the kspp tree, today's linux-next build (x86_64 >> > > > > allmodconfig) failed like this: >> > > > > >> > > > > cc1: error: plugin stackleak_plugin should be specified before -= fplugin-arg-stackleak_plugin-disable in the command line >> > > > > >> > > > > Maybe caused by commit >> > > > > >> > > > > a8b9eaddb9c0 ("gcc-plugins: Add STACKLEAK plugin for tracking = the kernel stack") >> > > > > >> > > > > I have used the kspp tree from next-20180726 for today. >> > > > >> > > > Well, that obviously didn't work since the tree hasn't changed for= a >> > > > few days. >> > > > >> > > > I can't see what has interacted to make this happen, so I have dro= pped >> > > > the kspp tree for today. >> > > >> > > Actually, it may have been caused by commit >> > > >> > > 0b3e336601b8 ("arm64: Add support for STACKLEAK gcc plugin") >> > > >> > > from the arm64 tree. >> > >> > Thanks, Stephen. I managed to reproduce this by merging for-next/kspp = from >> > Kees's tree and for-next/core from the arm64 tree. The failure happens= when >> > building the EFI stub, so the commit you mention above is almost certa= inly >> > the culprit. >> > >> > We build the stub with the following GCC invocation: >> > >> > gcc -Wp,-MD,drivers/firmware/efi/libstub/.efi-stub-helper.o.d -nostd= inc -isystem /usr/lib/gcc/x86_64-linux-gnu/4.9/include -I./arch/x86/include= -I./arch/x86/include/generated -I./include -I./arch/x86/include/uapi -I./= arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi= -include ./include/linux/kconfig.h -include ./include/linux/compiler_types= .h -D__KERNEL__ -mcmodel=3Dsmall -m64 -D__KERNEL__ -O2 -fPIC -fno-strict-al= iasing -mno-red-zone -mno-mmx -mno-sse -fshort-wchar -DDISABLE_BRANCH_PROFI= LING -D__NO_FORTIFY -ffreestanding -fno-stack-protector -fplugin-arg-stackl= eak_plugin-disable -fno-builtin -DKBUILD_BASENAME=3D'"efi_stub_helpe= r"' -DKBUILD_MODNAME=3D'"efi_stub_helper"' -c -o drivers/firmware/efi/libst= ub/.tmp_efi-stub-helper.o drivers/firmware/efi/libstub/efi-stub-helper.c >> > >> > so given that we're not passing any -fplugin=3D option anyway (because= we >> > override KBUILD_CFLAGS for the stub), I don't understand why we need >> > to the disable option at all. >> > >> > Laura? >> >> ... ah, but arm and arm64 inherit the old KBUILD_CFLAGS via the >> cflags-$(CONFIG_ARM64) and cflags-$(CONFIG_ARM) definitions, so they >> would be the places where we need to disable the plugin. > > i.e. something like the diff below. > > Will > > --->8 > > diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi= /libstub/Makefile > index 25dd2a14560d..f3700fe08908 100644 > --- a/drivers/firmware/efi/libstub/Makefile > +++ b/drivers/firmware/efi/libstub/Makefile > @@ -11,9 +11,11 @@ cflags-$(CONFIG_X86) +=3D -m$(BITS) -D__KERNEL= __ -O2 \ > -fPIC -fno-strict-aliasing -mno-red-zo= ne \ > -mno-mmx -mno-sse -fshort-wchar > > -cflags-$(CONFIG_ARM64) :=3D $(subst -pg,,$(KBUILD_CFLAGS)) -fpie > +cflags-$(CONFIG_ARM64) :=3D $(subst -pg,,$(KBUILD_CFLAGS)) -fpie= \ > + $(DISABLE_STACKLEAK_PLUGIN) > cflags-$(CONFIG_ARM) :=3D $(subst -pg,,$(KBUILD_CFLAGS)) \ > - -fno-builtin -fpic -mno-single-pic-bas= e > + -fno-builtin -fpic -mno-single-pic-bas= e \ > + $(DISABLE_STACKLEAK_PLUGIN) > > cflags-$(CONFIG_EFI_ARMSTUB) +=3D -I$(srctree)/scripts/dtc/libfdt > > @@ -21,7 +23,6 @@ KBUILD_CFLAGS :=3D $(cflags-y) -DDISABL= E_BRANCH_PROFILING \ > -D__NO_FORTIFY \ > $(call cc-option,-ffreestanding) \ > $(call cc-option,-fno-stack-protector)= \ > - $(DISABLE_STACKLEAK_PLUGIN) > > GCOV_PROFILE :=3D n > KASAN_SANITIZE :=3D n Ah! Thanks for tracking this down! -Kees --=20 Kees Cook Pixel Security