netdev - Re: net/sctp: vmalloc allocation failure in sctp_setsockopt/xt_alloc_table

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Message-ID: <20161128175626.GD29839@hmsreliant.think-freely.org>
Date:   Mon, 28 Nov 2016 12:56:26 -0500
From:   Neil Horman <nhorman@...driver.com>
To:     Florian Westphal <fw@...len.de>
Cc:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Vlad Yasevich <vyasevich@...il.com>,
        linux-sctp@...r.kernel.org, netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Patrick McHardy <kaber@...sh.net>,
        Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
        "David S. Miller" <davem@...emloft.net>,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Kostya Serebryany <kcc@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: net/sctp: vmalloc allocation failure in
 sctp_setsockopt/xt_alloc_table_info

On Mon, Nov 28, 2016 at 06:47:10PM +0100, Florian Westphal wrote:
> Neil Horman <nhorman@...driver.com> wrote:
> > I'm not sure I agree with that.  Generally speaking it seems like the right
> > thing to do, if you want to avoid filling logs with warnings, but this is the
> > sort of error that is going to be accompanied by severe service interruption.
> > I'd rather see a reason behind that in the logs, than just have it occur
> > silently.
> 
> Its not silent -- the setsockopt call will fail and userspace should
> display an error.
> 
Thats not true.  If the OOM succedes in freeing enough memory to fulfill the
request the setsockopt may complete without error, you're just left with a
killed process...somewhere.  Thats seems a bit dodgy to me

Not saying it has to be a full stack trace, but some log annotation that shows
the oom killer got invoked seems called for here

Neil

> So I agree with Marcelo, lets suppress the oom spew here.
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