linux-kernel - Re: [PATCH 2/2] bpf: sockmap, fix double-free

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Date:   Thu, 17 May 2018 10:26:21 -0700
From:   John Fastabend <john.fastabend@...il.com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] bpf: sockmap, fix double-free

On 05/17/2018 07:11 AM, Gustavo A. R. Silva wrote:
> `e' is being freed twice.
> 
> Fix this by removing one of the kfree() calls.
> 
> Addresses-Coverity-ID: 1468983 ("Double free")
> Fixes: 81110384441a ("bpf: sockmap, add hash map support")
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
> ---
>  kernel/bpf/sockmap.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/kernel/bpf/sockmap.c b/kernel/bpf/sockmap.c
> index 41b41fc..c682669 100644
> --- a/kernel/bpf/sockmap.c
> +++ b/kernel/bpf/sockmap.c
> @@ -1823,7 +1823,6 @@ static int __sock_map_ctx_update_elem(struct bpf_map *map,
>  	write_unlock_bh(&sock->sk_callback_lock);
>  	return err;
>  out_free:
> -	kfree(e);
>  	smap_release_sock(psock, sock);
>  out_progs:
>  	if (verdict)
> 

Thanks. This can happen when a user tries to add a kTLS socket to a
sockmap. We need to add some tests for kTLS + sockmap cases.

Acked-by: John Fastabend <john.fastabend@...il.com>