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From:   Zhengchao Shao <shaozhengchao@huawei.com>
To:     <linux-wireless@vger.kernel.org>, <netdev@vger.kernel.org>,
        <johannes@sipsolutions.net>, <davem@davemloft.net>,
        <edumazet@google.com>, <kuba@kernel.org>, <pabeni@redhat.com>
CC:     <weiyongjun1@huawei.com>, <yuehaibing@huawei.com>,
        <shaozhengchao@huawei.com>
Subject: [PATCH net,v2] wifi: mac80211: fix WARNING in ieee80211_link_info_change_notify()
Date:   Fri, 1 Sep 2023 11:53:01 +0800
Message-ID: <20230901035301.3473463-1-shaozhengchao@huawei.com>
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Syz reports the following WARNING:
wlan0: Failed check-sdata-in-driver check, flags: 0x0
WARNING: CPU: 3 PID: 5384 at net/mac80211/main.c:287
ieee80211_link_info_change_notify+0x1c2/0x230
Modules linked in:
RIP: 0010:ieee80211_link_info_change_notify+0x1c2/0x230
Call Trace:
<TASK>
ieee80211_set_mcast_rate+0x3e/0x50
nl80211_set_mcast_rate+0x316/0x650
genl_family_rcv_msg_doit+0x20b/0x300
genl_rcv_msg+0x39f/0x6a0
netlink_rcv_skb+0x13b/0x3b0
genl_rcv+0x24/0x40
netlink_unicast+0x4a2/0x740
netlink_sendmsg+0x83e/0xce0
sock_sendmsg+0xc5/0x100
____sys_sendmsg+0x583/0x690
___sys_sendmsg+0xe8/0x160
__sys_sendmsg+0xbf/0x160
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
</TASK>

The execution process is as follows:
Thread A:
ieee80211_open()
    ieee80211_do_open()
        drv_add_interface()     //set IEEE80211_SDATA_IN_DRIVER flag
...
rtnl_newlink
    do_setlink
	dev_change_flags
            ...
            __dev_close_many
                ieee80211_stop()
                    ieee80211_do_stop()
                        drv_remove_interface() //clear flag
...
nl80211_set_mcast_rate()
    ieee80211_set_mcast_rate()
        ieee80211_link_info_change_notify()
            check_sdata_in_driver() //WARNING because flag is cleared

When the wlan device stops, the IEEE80211_SDATA_IN_ DRIVER flag is cleared.
And then after the set mcast rate command is executed, WARNING is generated
because the flag bit has been already cleared.

Fixes: 591e73ee3f73 ("wifi: mac80211: properly skip link info driver update")
Reported-by: syzbot+bce2ca140cc00578ed07@syzkaller.appspotmail.com
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
---
v2: modify commit info
---
 net/mac80211/main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 24315d7b3126..f79e2343dddd 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -285,6 +285,9 @@ void ieee80211_link_info_change_notify(struct ieee80211_sub_if_data *sdata,
 	if (!changed || sdata->vif.type == NL80211_IFTYPE_AP_VLAN)
 		return;
 
+	if (!ieee80211_sdata_running(sdata))
+		return;
+
 	if (!check_sdata_in_driver(sdata))
 		return;
 
-- 
2.34.1