linux-kernel - Re: 4.17.x won't boot due to "x86/boot/compressed/64: Handle 5-level paging boot if kernel is above 4G"

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180704150857.szamkvy6jx3fqxlf@kshutemo-mobl1>
Date:   Wed, 4 Jul 2018 18:08:57 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Gabriel C <nix.or.die@...il.com>
Cc:     Benjamin Gilbert <bgilbert@...hat.com>,
        linux-x86_64@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>,
        bero@...dev.ch, Andi Kleen <ak@...ux.intel.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <michal.lkml@...kovi.net>
Subject: Re: 4.17.x won't boot due to "x86/boot/compressed/64: Handle 5-level
 paging boot if kernel is above 4G"

On Tue, Jul 03, 2018 at 05:21:50PM +0300, Kirill A. Shutemov wrote:
> On Tue, Jul 03, 2018 at 03:44:03PM +0300, Kirill A. Shutemov wrote:
> > On Tue, Jul 03, 2018 at 01:24:49PM +0200, Gabriel C wrote:
> > > 2018-07-01 23:32 GMT+02:00 Benjamin Gilbert <bgilbert@...hat.com>:
> > > > On Sun, Jul 01, 2018 at 05:15:59PM -0400, Benjamin Gilbert wrote:
> > > >> 4.17 kernels built with the CoreOS Container Linux toolchain and kconfig,
> > > >> up to and including 4.17.3, fail to boot on AMD64 running in (at least)
> > > >> QEMU/KVM.  No messages are shown post-GRUB; the VM instantly reboots.
> > > >> Reverting commit 194a9749c73d ("x86/boot/compressed/64: Handle 5-level
> > > >> paging boot if kernel is above 4G") fixes it.  I've attached our kernel
> > > >> config for reference, and am happy to test patches, provide sample QCOW
> > > >> images, etc.
> > > >
> > > 
> > > Also see https://bugzilla.kernel.org/show_bug.cgi?id=200385 ,
> > > 
> > > 0a1756bd2897951c03c1cb671bdfd40729ac2177 is acting up
> > > too with the same symptoms
> > 
> > I tracked it down to -flto in LDFLAGS. I'll look more into this.
> 
> -flto in LDFLAGS screws up this part of paging_prepare():

+Masahiro, Michal.

I've got it wrong. *Any* LDFLAGS option passed to make this way:

  make LDFLAGS="..."

would cause a issue. Even empty.

It overrides all assignments to the variable in the makefile.
As result the image is built without -pie and linker doesn't generate
position independed code.

Looks like the patch below helps, but my make-fu is poor.
I don't see many override directives in kernel makefiles.
It makes me think that there's a better way to fix this.

Hm?
 
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index fa42f895fdde..4f24baa8cdeb 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -42,16 +42,16 @@ KBUILD_AFLAGS  := $(KBUILD_CFLAGS) -D__ASSEMBLY__
 GCOV_PROFILE := n
 UBSAN_SANITIZE :=n
 
-LDFLAGS := -m elf_$(UTS_MACHINE)
+override LDFLAGS := -m elf_$(UTS_MACHINE)
 # Compressed kernel should be built as PIE since it may be loaded at any
 # address by the bootloader.
 ifeq ($(CONFIG_X86_32),y)
-LDFLAGS += $(call ld-option, -pie) $(call ld-option, --no-dynamic-linker)
+override LDFLAGS += $(call ld-option, -pie) $(call ld-option, --no-dynamic-linker)
 else
 # To build 64-bit compressed kernel as PIE, we disable relocation
 # overflow check to avoid relocation overflow error with a new linker
 # command-line option, -z noreloc-overflow.
-LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \
+override LDFLAGS += $(shell $(LD) --help 2>&1 | grep -q "\-z noreloc-overflow" \
 	&& echo "-z noreloc-overflow -pie --no-dynamic-linker")
 endif
 LDFLAGS_vmlinux := -T
-- 
 Kirill A. Shutemov