linux-kernel - Re: net: heap out-of-bounds in fib6_clean_node/rt6_fill_node/fib6_age/fib6_prune

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Message-ID: <CAAeHK+zWO1COcZDp9q4eHP9YN9Qv8CXLOJu8dJgCbihcFSK3jg@mail.gmail.com>
Date:   Thu, 20 Apr 2017 14:10:03 +0200
From:   Andrey Konovalov <andreyknvl@...gle.com>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     David Ahern <dsa@...ulusnetworks.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Mahesh Bandewar <maheshb@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        David Miller <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        James Morris <jmorris@...ei.org>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Patrick McHardy <kaber@...sh.net>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        syzkaller <syzkaller@...glegroups.com>
Subject: Re: net: heap out-of-bounds in fib6_clean_node/rt6_fill_node/fib6_age/fib6_prune_clone

On Thu, Apr 20, 2017 at 10:35 AM, Dmitry Vyukov <dvyukov@...gle.com> wrote:
> On Thu, Apr 20, 2017 at 1:51 AM, David Ahern <dsa@...ulusnetworks.com> wrote:
>> On 4/19/17 5:47 PM, Cong Wang wrote:
>>> On Wed, Apr 19, 2017 at 9:12 AM, Andrey Konovalov <andreyknvl@...gle.com> wrote:
>>>>
>>>> Anyway, I just finished simplifying the reproducer. Give this one a try.
>>>
>>> Thanks for providing such a minimal reproducer!
>>>
>>> The following patch could fix this crash, but I am not 100% sure if we should
>>> just clear these bits or reject them with an errno.
>>>
>>> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
>>> index 9db14189..cf524c2 100644
>>> --- a/net/ipv6/route.c
>>> +++ b/net/ipv6/route.c
>>> @@ -2086,7 +2086,7 @@ static struct rt6_info
>>> *ip6_route_info_create(struct fib6_config *cfg)
>>>         } else
>>>                 rt->rt6i_prefsrc.plen = 0;
>>>
>>> -       rt->rt6i_flags = cfg->fc_flags;
>>> +       rt->rt6i_flags = cfg->fc_flags & ~(RTF_PCPU | RTF_CACHE);
>>>
>>>  install_route:
>>>         rt->dst.dev = dev;
>>>
>>
>> I sent a patch returning EINVAL if RTF_PCPU is set in fc_flags
>
>
> Andrey, does it fix the other crashes?

No, still see them.

I'm working on reproducing those.