netdev - Re: Use after free in __dst_destroy_metrics

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Date:   Fri, 8 Sep 2017 09:10:20 -0700
From:   Cong Wang <xiyou.wangcong@...il.com>
To:     Subash Abhinov Kasiviswanathan <subashab@...eaurora.org>
Cc:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Lorenzo Colitti <lorenzo@...gle.com>
Subject: Re: Use after free in __dst_destroy_metrics_generic

On Thu, Sep 7, 2017 at 5:52 PM, Subash Abhinov Kasiviswanathan
<subashab@...eaurora.org> wrote:
> We are seeing a possible use after free in ip6_dst_destroy.
>
> It appears as if memory of the __DST_METRICS_PTR(old) was freed in some path
> and allocated
> to ion driver. ion driver has also freed it. Finally the memory is freed by
> the
> fib gc and crashes since it is already deallocated.

Does the attach (compile-only) patch help anything?

>From my _quick_ glance, it seems we miss the refcnt'ing
right in __dst_destroy_metrics_generic().

Thanks!

View attachment "dst-metrics-ref.diff" of type "text/plain" (661 bytes)