| Message ID | tencent_7142963A37944B4A74EF76CD66EA3C253609@qq.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | b4cd80b0338945a94972ac3ed54f8338d2da2076 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,V4] mptcp: pm: Fix uaf in __timer_delete_sync | expand |
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) <matttbe@kernel.org> > Signed-off-by: Edward Adam Davis <eadavis@qq.com> Acked-by: Paolo Abeni <pabeni@redhat.com>
Hi Edward, On 10/09/2024 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) <matttbe@kernel.org> > Signed-off-by: Edward Adam Davis <eadavis@qq.com> It looks also good to me, but no need for me to add a reviewed-by tag I suppose. This v4 can be applied in netdev directly. Cheers, Matt
Hello: This patch was applied to netdev/net.git (main) by Jakub Kicinski <kuba@kernel.org>: On Tue, 10 Sep 2024 17:58:56 +0800 you 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) > > [...] Here is the summary with links: - [net,V4] mptcp: pm: Fix uaf in __timer_delete_sync https://git.kernel.org/netdev/net/c/b4cd80b03389 You are awesome, thank you!
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 3e4ad801786f..f195b577c367 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -331,15 +331,21 @@ mptcp_pm_del_add_timer(struct mptcp_sock *msk, { struct mptcp_pm_add_entry *entry; struct sock *sk = (struct sock *)msk; + struct timer_list *add_timer = NULL; spin_lock_bh(&msk->pm.lock); entry = mptcp_lookup_anno_list_by_saddr(msk, addr); - if (entry && (!check_id || entry->addr.id == addr->id)) + if (entry && (!check_id || entry->addr.id == addr->id)) { entry->retrans_times = ADD_ADDR_RETRANS_MAX; + add_timer = &entry->add_timer; + } + if (!check_id && entry) + list_del(&entry->list); spin_unlock_bh(&msk->pm.lock); - if (entry && (!check_id || entry->addr.id == addr->id)) - sk_stop_timer_sync(sk, &entry->add_timer); + /* no lock, because sk_stop_timer_sync() is calling del_timer_sync() */ + if (add_timer) + sk_stop_timer_sync(sk, add_timer); return entry; } @@ -1430,7 +1436,6 @@ static bool remove_anno_list_by_saddr(struct mptcp_sock *msk, entry = mptcp_pm_del_add_timer(msk, addr, false); if (entry) { - list_del(&entry->list); kfree(entry); return true; }
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) <matttbe@kernel.org> Signed-off-by: Edward Adam Davis <eadavis@qq.com> --- net/mptcp/pm_netlink.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)