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Date:   Sat, 28 Sep 2019 14:41:29 +0200
From:   Ingo Molnar <mingo@kernel.org>
To:     Randy Dunlap <rdunlap@infradead.org>
Cc:     Andreas Smas <andreas@lonelycoder.com>,
        linux-kernel@vger.kernel.org, X86 ML <x86@kernel.org>
Subject: Re: x86/purgatory: undefined symbol __stack_chk_fail
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* Randy Dunlap <rdunlap@infradead.org> wrote:

> On 9/3/19 8:50 AM, Andreas Smas wrote:
> > Hi,
> > 
> > For me, kernels built including this commit
> > b059f801a937 (x86/purgatory: Use CFLAGS_REMOVE rather than reset KBUILD_CFLAGS)
> > 
> > results in kexec() failing to load the kernel:
> > 
> > kexec: Undefined symbol: __stack_chk_fail
> > kexec-bzImage64: Loading purgatory failed
> > 
> > Can be seen:
> > 
> > $ readelf -a arch/x86/purgatory/purgatory.ro | grep UND
> >      0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND
> >     51: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND __stack_chk_fail
> > 
> > Using: gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1)
> > 
> > Adding -ffreestanding or -fno-stack-protector to ccflags-y in
> > arch/x86/purgatory/Makefile
> > fixes the problem. Not sure which would be preferred.
> > 
> 
> Hi,
> Do you have a kernel .config file that causes this?
> I can't seem to reproduce it.

Does it go away with this fix in x86/urgent:

  ca14c996afe7: ("x86/purgatory: Disable the stackleak GCC plugin for the purgatory")

  git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/urgent

?

Thanks,

	Ingo