linux-kernel - Re: [PATCH v2 2/3] MIPS: Move kernel head into a standalone section

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: <20200527200522.23c4e86f@halation.net.flygoat.com>
Date:   Wed, 27 May 2020 20:05:22 +0800
From:   Jiaxun Yang <jiaxun.yang@...goat.com>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>
Cc:     linux-mips@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        Borislav Petkov <bp@...e.de>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Fangrui Song <maskray@...gle.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] MIPS: Move kernel head into a standalone section

On Wed, 27 May 2020 13:53:54 +0200
Thomas Bogendoerfer <tsbogend@...ha.franken.de> wrote:

> On Wed, May 27, 2020 at 02:34:33PM +0800, Jiaxun Yang wrote:
> > That's what already done by Arm64 and other architectures.
> > That would allow us put more things like PE headers safely into
> > the header.
> > 
> > Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
> > ---
> >  arch/mips/kernel/head.S        | 4 ++--
> >  arch/mips/kernel/vmlinux.lds.S | 8 ++++++--
> >  2 files changed, 8 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S
> > index c7c2795837e7..8081a905a71c 100644
> > --- a/arch/mips/kernel/head.S
> > +++ b/arch/mips/kernel/head.S
> > @@ -59,6 +59,8 @@
> >  #endif
> >  	.endm
> >  
> > +	__HEAD
> > +_head:
> >  #ifndef CONFIG_NO_EXCEPT_FILL
> >  	/*
> >  	 * Reserved space for exception handlers.  
> 
> I'm adding the missing piece, why this change ist broken:
> 
>          * Necessary for machines which link their kernels at KSEG0.
> 
> by putting something in front of that will probably break platforms
> making use of "feature". If we can make sure, we don't need it
> anymore, we should first remove this and then add __HEAD part.

__HEAD is just marking the section of code.
It will not add anything to the binary.

Btw: I just noticed this patch may break relocatable kernel. I'll delay
it for next merge window.

Thanks.

> 
> Thomas.
> 

--
Jiaxun Yang