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Message-ID: <b2272b72-d207-4393-9245-31ad7628be09@kernel.org> Date: Fri, 6 Sep 2024 20:55:20 +0200 From: Matthieu Baerts <matttbe@...nel.org> To: Edward Adam Davis <eadavis@...com> Cc: davem@...emloft.net, edumazet@...gle.com, geliang@...nel.org, kuba@...nel.org, linux-kernel@...r.kernel.org, martineau@...nel.org, mptcp@...ts.linux.dev, netdev@...r.kernel.org, pabeni@...hat.com, syzbot+f3a31fb909db9b2a5c4d@...kaller.appspotmail.com, syzkaller-bugs@...glegroups.com Subject: Re: [PATCH net v3] mptcp: pm: Fix uaf in __timer_delete_sync Hi Edward, On 05/09/2024 14:27, 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". > > Fixes: 00cfd77b9063 ("mptcp: retransmit ADD_ADDR when timeout") > Cc: stable@...r.kernel.org > Reported-and-tested-by: syzbot+f3a31fb909db9b2a5c4d@...kaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=f3a31fb909db9b2a5c4d > Signed-off-by: Matthieu Baerts (NGI0) <matttbe@...nel.org> According to the doc [1], a 'Co-dev' tag is supposed to be added before this SoB: Co-developed-by: Matthieu Baerts (NGI0) <matttbe@...nel.org> But I'm sure that's fine without it. [1] https://docs.kernel.org/process/submitting-patches.html#when-to-use-acked-by-cc-and-co-developed-by This v3 now looks good to me. I don't know if it needs to be reviewed by someone else as I'm now listed as co-developed. Cheers, Matt -- Sponsored by the NGI0 Core fund.
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