netdev - Re: [PATCH net] ipv6: Fix cleanup ordering on inet6

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Message-ID: <1515689336.12097.14.camel@codethink.co.uk>
Date:   Thu, 11 Jan 2018 16:48:56 +0000
From:   Ben Hutchings <ben.hutchings@...ethink.co.uk>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: Re: [PATCH net] ipv6: Fix cleanup ordering on inet6_init() error
 path

On Wed, 2018-01-10 at 14:25 -0800, Cong Wang wrote:
> On Tue, Jan 9, 2018 at 10:21 AM, Ben Hutchings
> <ben.hutchings@...ethink.co.uk> wrote:
> > Commit 15e668070a64 reordered the initialisation in inet6_init() to
> > fix a crash on an error path further down the call stack.  It also
> > reordered cleanup on the error path in inet6_init(), but the result
> > is not the reverse of the initialisation order.  This presumably
> > can result in a resource leak or crash in some error
> > cases.  Reorder
> > cleanup again to fix this.
> 
> Can you be specific on what resource we leak here?

If icmpv6_init() fails, after ip6_mr_init(), then ip6_mr_cleanup() is
not called.

Also, if ip6_mr_init() fails, we don't unregister inet6_net_ops.  I
think that will result in a crash - immediately if ipv6 is a module,
otherwise when the next net namespace is created.

> Also, it looks like you not just revert the order changed in commit
> 15e668070a64, but also you move  icmpv6_cleanup() even earlier.

So should I add another Fixes: there?

Ben.

-- 
Ben Hutchings
Software Developer, Codethink Ltd.