linux-kernel - Re: [PATCH v13 11/11] arm64: Select HAVE_RELIABLE

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: <1a0e19db-a7f8-4c8e-0163-398fcd364d54@linux.microsoft.com>
Date:   Wed, 26 Jan 2022 11:14:10 -0600
From:   "Madhavan T. Venkataraman" <madvenka@...ux.microsoft.com>
To:     "nobuta.keiya@...itsu.com" <nobuta.keiya@...itsu.com>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "jpoimboe@...hat.com" <jpoimboe@...hat.com>,
        "ardb@...nel.org" <ardb@...nel.org>,
        "sjitindarsingh@...il.com" <sjitindarsingh@...il.com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will@...nel.org" <will@...nel.org>,
        "jmorris@...ei.org" <jmorris@...ei.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "live-patching@...r.kernel.org" <live-patching@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v13 11/11] arm64: Select HAVE_RELIABLE_STACKTRACE

On 1/26/22 04:20, nobuta.keiya@...itsu.com wrote:
>> I have not seen any activity on that in a long time. IIRC, Julien quit RedHat.
>> I don't know if anyone else has taken over this work in RedHat.
>>
>> Sorry, I don't have any more information.
>>
>> Madhavan
> 
> Thanks for your information.
> 
> By the way, I'm considering test code for arch_stack_walk_reliable().
> Specifically, I apply Suraj's patch to enable livepatch, and added a function
> that sleeps between SYM_CODE_START and SYM_CODE_END, then livepatch
> checks if the task has an unreliable stack.
> For now my internal test code working correctly, but my Kconfig excludes
> STACK_VALIDATION dependency.
> 
> It seems that objtool will not be enabled yet, so I would like to test it easier.
> If you are already testing with this patch, could you tell me how to do it?
> 
> 

For now, I have an instrumented kernel that directly invokes arch_stack_walk_reliable()
from various places in the kernel (interrupt handlers, exception handlers, ftrace entry,
kprobe handler, etc). I also have a test driver to induce conditions like null pointer
dereference. I use this to test different cases where arch_stack_walk_reliable() should
return an error.

As for livepatch testing, I have enhanced objtool and the kernel so the frame pointer can
be validated dynamically rather than statically. I have tested various different livepatch
selftests successfully. I have also written my own livepatch tests to add to the selftests.
I am currently working on preparing an RFC patch series for review. Basically, this series
implements STACK_VALIDATION in a different way.

I plan to publish my work soon (hopefully Feb 2022). I was going to do in December. However,
my workload in Microsoft did not permit me to do that. I am also planning to set up a github
repo so people can try out my changes, if they are interested.

So, stay tuned.

Madhavan