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Message-ID: <tencent_274B82754376EF66A23C0D37029644374609@qq.com>
Date: Tue, 3 Sep 2024 23:09:55 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+f3a31fb909db9b2a5c4d@...kaller.appspotmail.com
Cc: davem@...emloft.net,
edumazet@...gle.com,
geliang@...nel.org,
kuba@...nel.org,
linux-kernel@...r.kernel.org,
martineau@...nel.org,
matttbe@...nel.org,
mptcp@...ts.linux.dev,
netdev@...r.kernel.org,
pabeni@...hat.com,
syzkaller-bugs@...glegroups.com
Subject: [PATCH] mptcp: pm: Fix uaf in __timer_delete_sync
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).
Reported-and-tested-by: syzbot+f3a31fb909db9b2a5c4d@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f3a31fb909db9b2a5c4d
Signed-off-by: Edward Adam Davis <eadavis@...com>
---
net/mptcp/pm_netlink.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c
index 3e4ad801786f..d28bf0c9ad66 100644
--- a/net/mptcp/pm_netlink.c
+++ b/net/mptcp/pm_netlink.c
@@ -336,11 +336,12 @@ mptcp_pm_del_add_timer(struct mptcp_sock *msk,
entry = mptcp_lookup_anno_list_by_saddr(msk, addr);
if (entry && (!check_id || entry->addr.id == addr->id))
entry->retrans_times = ADD_ADDR_RETRANS_MAX;
- spin_unlock_bh(&msk->pm.lock);
if (entry && (!check_id || entry->addr.id == addr->id))
sk_stop_timer_sync(sk, &entry->add_timer);
+ spin_unlock_bh(&msk->pm.lock);
+
return entry;
}
--
2.43.0
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