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From: Jiaxun Yang <jiaxun.yang@flygoat.com>
To: James Hogan <jhogan@kernel.org>, Huacai Chen <chenhc@lemote.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Ralf Baechle <ralf@linux-mips.org>,
	linux-mips@linux-mips.org, Russell King <linux@arm.linux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	Yoshinori Sato <ysato@users.sourceforge.jp>,
	Rich Felker <dalias@libc.org>,
	linux-sh@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH V3] ZBOOT: fix stack protector in compressed boot phase
Date: Fri, 23 Mar 2018 11:50:55 +0800	[thread overview]
Message-ID: <1521777055.1510.9.camel@flygoat.com> (raw)
In-Reply-To: <20180322222107.GJ13126@saruman>

在 2018-03-22四的 22:21 +0000，James Hogan写道：
> On Fri, Mar 16, 2018 at 03:55:16PM +0800, Huacai Chen wrote:
> > diff --git a/arch/mips/boot/compressed/decompress.c
> > b/arch/mips/boot/compressed/decompress.c
> > index fdf99e9..5ba431c 100644
> > --- a/arch/mips/boot/compressed/decompress.c
> > +++ b/arch/mips/boot/compressed/decompress.c
> > @@ -78,11 +78,6 @@ void error(char *x)
> >  
> >  unsigned long __stack_chk_guard;
> 
> ...
> 
> > diff --git a/arch/mips/boot/compressed/head.S
> > b/arch/mips/boot/compressed/head.S
> > index 409cb48..00d0ee0 100644
> > --- a/arch/mips/boot/compressed/head.S
> > +++ b/arch/mips/boot/compressed/head.S
> > @@ -32,6 +32,10 @@ start:
> >  	bne	a2, a0, 1b
> >  	 addiu	a0, a0, 4
> >  
> > +	PTR_LA	a0, __stack_chk_guard
> > +	PTR_LI	a1, 0x000a0dff
> > +	sw	a1, 0(a0)
> 

Hi James

Huacai Can't reply this mail. His chenhc@lemote.com is blcoked by
Linux-MIPS mailing list while his Gmail didn't receive this email, so
I'm replying for him.

> Should that not be LONG_S? Otherwise big endian MIPS64 would get a
> word-swapped canary (which is probably mostly harmless, but still).

Yes, he said it's considerable.

> 
> Also I think it worth mentioning in the commit message the MIPS
> configuration you hit this with, presumably a Loongson one? For me
> decompress_kernel() gets a stack guard on loongson3_defconfig, but
> not
> malta_defconfig or malta_defconfig + 64-bit. I presume its sensitive
> to
> the compiler inlining stuff into decompress_kernel() or something
> such
> that it suddenly qualifies for a stack guard.

Have you tested with CONFIG_CC_STACKPROTECTOR_STRONG=y ?
Huacai reproduced the issue by this[1] config with GCC 4.9.

[1] https://github.com/loongson-community/linux-stable/blob/rebase-4.14
/arch/mips/configs/loongson3_defconfig

> 
> Cheers
> James

  reply	other threads:[~2018-03-23  3:59 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <CGME20180316075352epcas5p3d95b13f9382ff7bbce83b8177e8e3ad6@epcas5p3.samsung.com>
2018-03-16  7:55 ` [PATCH V3] ZBOOT: fix stack protector in compressed boot phase Huacai Chen
2018-03-16 22:13   ` Andrew Morton
2018-03-16 23:13     ` Rich Felker
2018-03-22 22:21   ` James Hogan
2018-03-23  3:50     ` Jiaxun Yang [this message]
2018-03-23 21:08       ` James Hogan
2018-03-23  8:14   ` Marek Szyprowski

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