linux-kernel - Re: [PATCH] kernel/sys.c: fix possible spectre-v1 in do

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-next>] [day] [month] [year] [list]

Message-ID: <20190528071053.GL11013@uranus>
Date:   Tue, 28 May 2019 10:10:53 +0300
From:   Cyrill Gorcunov <gorcunov@...il.com>
To:     Dianzhang Chen <dianzhangchen0@...il.com>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kernel/sys.c: fix possible spectre-v1 in do_prlimit()

On Tue, May 28, 2019 at 10:37:10AM +0800, Dianzhang Chen wrote:
> Hi,
> Because when i reply your email，i always get 'Message rejected' from
> gmail(get this rejection from all the recipients). I still don't know
> how to deal with it, so i reply your email here:

Hi! This is weird. Next time simply reply to LKML (I CC'ed it back).

> Because of speculative execution, the attacker can bypass the bound
> check `if (resource >= RLIM_NLIMITS)`.

And then misprediction get detected and execution is dropped. So I
still don't see a problem here, since we don't leak info even in
such case.

That said I don't mind for this patch but rather in a sake of
code clarity, not because of spectre issue since it has
nothing to do here.

> as for array_index_nospec(index, size), it will clamp the index within
> the range of [0, size), and attacker can't exploit speculative
> execution to make the index out of range [0, size).
> 
> 
> For more detail, please check the link below:
> 
> https://github.com/torvalds/linux/commit/f3804203306e098dae9ca51540fcd5eb700d7f40