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[146.241.69.130]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42caeb32678sm108194315e9.16.2024.09.10.04.27.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 10 Sep 2024 04:27:12 -0700 (PDT) Message-ID: <1cd88b74-5329-4aeb-8917-e291be104ea0@redhat.com> Date: Tue, 10 Sep 2024 13:27:10 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net V4] mptcp: pm: Fix uaf in __timer_delete_sync To: Edward Adam Davis Cc: davem@davemloft.net, edumazet@google.com, geliang@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, martineau@kernel.org, matttbe@kernel.org, mptcp@lists.linux.dev, netdev@vger.kernel.org, syzbot+f3a31fb909db9b2a5c4d@syzkaller.appspotmail.com, syzkaller-bugs@googlegroups.com References: Content-Language: en-US From: Paolo Abeni In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 9/10/24 11:58, Edward Adam Davis wrote: > There are two paths to access mptcp_pm_del_add_timer, result in a race > condition: > > CPU1 CPU2 > ==== ==== > net_rx_action > napi_poll netlink_sendmsg > __napi_poll netlink_unicast > process_backlog netlink_unicast_kernel > __netif_receive_skb genl_rcv > __netif_receive_skb_one_core netlink_rcv_skb > NF_HOOK genl_rcv_msg > ip_local_deliver_finish genl_family_rcv_msg > ip_protocol_deliver_rcu genl_family_rcv_msg_doit > tcp_v4_rcv mptcp_pm_nl_flush_addrs_doit > tcp_v4_do_rcv mptcp_nl_remove_addrs_list > tcp_rcv_established mptcp_pm_remove_addrs_and_subflows > tcp_data_queue remove_anno_list_by_saddr > mptcp_incoming_options mptcp_pm_del_add_timer > mptcp_pm_del_add_timer kfree(entry) > > In remove_anno_list_by_saddr(running on CPU2), after leaving the critical > zone protected by "pm.lock", the entry will be released, which leads to the > occurrence of uaf in the mptcp_pm_del_add_timer(running on CPU1). > > Keeping a reference to add_timer inside the lock, and calling > sk_stop_timer_sync() with this reference, instead of "entry->add_timer". > > Move list_del(&entry->list) to mptcp_pm_del_add_timer and inside the pm lock, > do not directly access any members of the entry outside the pm lock, which > can avoid similar "entry->x" uaf. > > Fixes: 00cfd77b9063 ("mptcp: retransmit ADD_ADDR when timeout") > Cc: stable@vger.kernel.org > Reported-and-tested-by: syzbot+f3a31fb909db9b2a5c4d@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=f3a31fb909db9b2a5c4d > Signed-off-by: Matthieu Baerts (NGI0) > Signed-off-by: Edward Adam Davis Acked-by: Paolo Abeni