From: Segher Boessenkool <segher@kernel.crashing.org>
To: David Laight <David.Laight@aculab.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>,
Xiaoming Ni <nixiaoming@huawei.com>,
"ravi.bangoria@linux.ibm.com" <ravi.bangoria@linux.ibm.com>,
"mikey@neuling.org" <mikey@neuling.org>,
"yanaijie@huawei.com" <yanaijie@huawei.com>,
"haren@linux.ibm.com" <haren@linux.ibm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"npiggin@gmail.com" <npiggin@gmail.com>,
"wangle6@huawei.com" <wangle6@huawei.com>,
"paulus@samba.org" <paulus@samba.org>,
"aneesh.kumar@linux.ibm.com" <aneesh.kumar@linux.ibm.com>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH] powerpc:Don't print raw EIP/LR hex values in dump_stack() and show_regs()
Date: Mon, 21 Dec 2020 11:12:28 -0600 [thread overview]
Message-ID: <20201221171228.GA2672@gate.crashing.org> (raw)
In-Reply-To: <ad814ccf34c14c76b45e50b6e7741c3a@AcuMS.aculab.com>
On Mon, Dec 21, 2020 at 04:42:23PM +0000, David Laight wrote:
> From: Segher Boessenkool
> > Sent: 21 December 2020 16:32
> >
> > On Mon, Dec 21, 2020 at 04:17:21PM +0100, Christophe Leroy wrote:
> > > Le 21/12/2020 à 04:27, Xiaoming Ni a écrit :
> > > >Since the commit 2b0e86cc5de6 ("powerpc/fsl_booke/32: implement KASLR
> > > >infrastructure"), the powerpc system is ready to support KASLR.
> > > >To reduces the risk of invalidating address randomization, don't print the
> > > >EIP/LR hex values in dump_stack() and show_regs().
> >
> > > I think your change is not enough to hide EIP address, see below a dump
> > > with you patch, you get "Faulting instruction address: 0xc03a0c14"
> >
> > As far as I can see the patch does nothing to the GPR printout. Often
> > GPRs contain code addresses. As one example, the LR is moved via a GPR
> > (often GPR0, but not always) for storing on the stack.
> >
> > So this needs more work.
>
> If the dump_stack() is from an oops you need the real EIP value
> on order to stand any chance of making headway.
Or at least the function name + offset, yes.
> Otherwise you might just as well just print 'borked - tough luck'.
Yes. ASLR is a house of cards. But that isn't constructive wrt this
patch :-)
Segher
next prev parent reply other threads:[~2020-12-21 17:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-21 3:27 [PATCH] powerpc:Don't print raw EIP/LR hex values in dump_stack() and show_regs() Xiaoming Ni
2020-12-21 15:17 ` Christophe Leroy
2020-12-21 16:31 ` Segher Boessenkool
2020-12-21 16:42 ` David Laight
2020-12-21 17:12 ` Segher Boessenkool [this message]
2020-12-22 13:45 ` Xiaoming Ni
2020-12-22 17:29 ` Segher Boessenkool
2020-12-22 17:45 ` Christophe Leroy
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