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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:     <alexander@wetzel-home.de>, <weiyongjun1@huawei.com>,
        <yuehaibing@huawei.com>, <shaozhengchao@huawei.com>
Subject: [PATCH] wifi: mac80211: fix general-protection-fault in ieee80211_subif_start_xmit()
Date:   Tue, 25 Oct 2022 20:32:50 +0800
Message-ID: <20221025123250.143952-1-shaozhengchao@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

When device is running and the interface status is changed, the gpf issue
is triggered. The problem triggering process is as follows:
Thread A:                           Thread B
ieee80211_runtime_change_iftype()   process_one_work()
    ...                                 ...
    ieee80211_do_stop()                 ...
    ...                                 ...
        sdata->bss = NULL               ...
        ...                             ieee80211_subif_start_xmit()
                                            ieee80211_multicast_to_unicast
                                    //!sdata->bss->multicast_to_unicast
                                      cause gpf issue

When the interface status is changed, the sending queue continues to send
packets. After the bss is set to NULL, the bss is accessed. As a result,
this causes a general-protection-fault issue.

The following is the stack information:
general protection fault, probably for non-canonical address
0xdffffc000000002f: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000178-0x000000000000017f]
Workqueue: mld mld_ifc_work
RIP: 0010:ieee80211_subif_start_xmit+0x25b/0x1310
Call Trace:
<TASK>
dev_hard_start_xmit+0x1be/0x990
__dev_queue_xmit+0x2c9a/0x3b60
ip6_finish_output2+0xf92/0x1520
ip6_finish_output+0x6af/0x11e0
ip6_output+0x1ed/0x540
mld_sendpack+0xa09/0xe70
mld_ifc_work+0x71c/0xdb0
process_one_work+0x9bf/0x1710
worker_thread+0x665/0x1080
kthread+0x2e4/0x3a0
ret_from_fork+0x1f/0x30
</TASK>

Fixes: 107395f9cf44 ("wifi: mac80211: Drop support for TX push path")
Reported-by: syzbot+c6e8fca81c294fd5620a@syzkaller.appspotmail.com
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
---
 net/mac80211/iface.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/mac80211/iface.c b/net/mac80211/iface.c
index dd9ac1f7d2ea..5a924459bfd1 100644
--- a/net/mac80211/iface.c
+++ b/net/mac80211/iface.c
@@ -1900,6 +1900,9 @@ static int ieee80211_runtime_change_iftype(struct ieee80211_sub_if_data *sdata,
 				  IEEE80211_QUEUE_STOP_REASON_IFTYPE_CHANGE);
 	synchronize_net();
 
+	if (sdata->dev)
+		netif_tx_stop_all_queues(sdata->dev);
+
 	ieee80211_do_stop(sdata, false);
 
 	ieee80211_teardown_sdata(sdata);
@@ -1922,6 +1925,9 @@ static int ieee80211_runtime_change_iftype(struct ieee80211_sub_if_data *sdata,
 	err = ieee80211_do_open(&sdata->wdev, false);
 	WARN(err, "type change: do_open returned %d", err);
 
+	if (sdata->dev)
+		netif_tx_start_all_queues(sdata->dev);
+
 	ieee80211_wake_vif_queues(local, sdata,
 				  IEEE80211_QUEUE_STOP_REASON_IFTYPE_CHANGE);
 	return ret;
-- 
2.17.1