From: Jakub Sitnicki <jakub@cloudflare.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
Cong Wang <cong.wang@bytedance.com>,
syzbot+7b6548ae483d6f4c64ae@syzkaller.appspotmail.com,
John Fastabend <john.fastabend@gmail.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Lorenz Bauer <lmb@cloudflare.com>
Subject: Re: [Patch bpf-next] sock_map: fix a potential use-after-free in sock_map_close()
Date: Mon, 12 Apr 2021 10:56:46 +0200 [thread overview]
Message-ID: <87pmyz3mpd.fsf@cloudflare.com> (raw)
In-Reply-To: <20210408030556.45134-1-xiyou.wangcong@gmail.com>
On Thu, Apr 08, 2021 at 05:05 AM CEST, Cong Wang wrote:
> From: Cong Wang <cong.wang@bytedance.com>
>
> The last refcnt of the psock can be gone right after
> sock_map_remove_links(), so sk_psock_stop() could trigger a UAF.
> The reason why I placed sk_psock_stop() there is to avoid RCU read
> critical section, and more importantly, some callee of
> sock_map_remove_links() is supposed to be called with RCU read lock,
> we can not simply get rid of RCU read lock here. Therefore, the only
> choice we have is to grab an additional refcnt with sk_psock_get()
> and put it back after sk_psock_stop().
>
> Reported-by: syzbot+7b6548ae483d6f4c64ae@syzkaller.appspotmail.com
> Fixes: 799aa7f98d53 ("skmsg: Avoid lock_sock() in sk_psock_backlog()")
> Cc: John Fastabend <john.fastabend@gmail.com>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> Cc: Jakub Sitnicki <jakub@cloudflare.com>
> Cc: Lorenz Bauer <lmb@cloudflare.com>
> Signed-off-by: Cong Wang <cong.wang@bytedance.com>
> ---
Acked-by: Jakub Sitnicki <jakub@cloudflare.com>
next prev parent reply other threads:[~2021-04-12 9:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-08 3:05 [Patch bpf-next] sock_map: fix a potential use-after-free in sock_map_close() Cong Wang
2021-04-09 0:26 ` John Fastabend
2021-04-09 4:08 ` Cong Wang
2021-04-09 19:42 ` John Fastabend
2021-04-12 8:56 ` Jakub Sitnicki [this message]
2021-04-12 15:40 ` patchwork-bot+netdevbpf
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