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From: Paolo Abeni <pabeni@redhat.com>
To: Young Xiao <92siuyang@gmail.com>,
	davem@davemloft.net, dsahern@gmail.com,
	roopa@cumulusnetworks.com, christian@brauner.io,
	khlebnikov@yandex-team.ru, netdev@vger.kernel.org
Subject: Re: [PATCH] net/neighbour: fix potential null pointer deference
Date: Fri, 31 May 2019 10:42:25 +0200	[thread overview]
Message-ID: <4105f63de712c8aa462aff6e3042d8689f68a33f.camel@redhat.com> (raw)
In-Reply-To: <1559291383-5814-1-git-send-email-92siuyang@gmail.com>

On Fri, 2019-05-31 at 16:29 +0800, Young Xiao wrote:
> There is a possible null pointer deference bugs in neigh_fill_info(),
> which is similar to the bug which was fixed in commit 6adc5fd6a142
> ("net/neighbour: fix crash at dumping device-agnostic proxy entries").
> 
> Signed-off-by: Young Xiao <92siuyang@gmail.com>
> ---
>  net/core/neighbour.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index dfa8710..33c3ff1 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c
> @@ -2440,7 +2440,7 @@ static int neigh_fill_info(struct sk_buff *skb, struct neighbour *neigh,
>  	ndm->ndm_pad2    = 0;
>  	ndm->ndm_flags	 = neigh->flags;
>  	ndm->ndm_type	 = neigh->type;
> -	ndm->ndm_ifindex = neigh->dev->ifindex;
> +	ndm->ndm_ifindex = neigh->dev ? neigh->dev->ifindex : 0;
>  
>  	if (nla_put(skb, NDA_DST, neigh->tbl->key_len, neigh->primary_key))
>  		goto nla_put_failure;

AFAICS, neigh->dev is requested to be != NULL at neighbour creation
time (see ___neigh_create()), so the above NULL ptr dereference looks
impossible. Am I missing something?

Thanks,

Paolo




  parent reply	other threads:[~2019-05-31  8:42 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-31  8:29 [PATCH] net/neighbour: fix potential null pointer deference Young Xiao
2019-05-31  8:41 ` Konstantin Khlebnikov
2019-05-31  8:42 ` Paolo Abeni [this message]
2019-05-31 14:56 ` Eric Dumazet

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