netdev - Re: [PATCH] net/neighbour: fix potential null pointer deference

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Date:   Fri, 31 May 2019 11:41:35 +0300
From:   Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:     Young Xiao <92siuyang@...il.com>, davem@...emloft.net,
        dsahern@...il.com, roopa@...ulusnetworks.com, christian@...uner.io,
        netdev@...r.kernel.org
Subject: Re: [PATCH] net/neighbour: fix potential null pointer deference

On 31.05.2019 11:29, 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").

Have you seen this in real life?
I see nobody who could produce neighbour with null device pointer._

> 
> Signed-off-by: Young Xiao <92siuyang@...il.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;
>