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From:   Nguyen Dinh Phi <phind.uet@gmail.com>
To:     johannes@sipsolutions.ne, davem@davemloft.net, kuba@kernel.org
Cc:     Nguyen Dinh Phi <phind.uet@gmail.com>,
        linux-wireless@vger.kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        linux-kernel-mentees@lists.linuxfoundation.org,
        syzbot+bbf402b783eeb6d908db@syzkaller.appspotmail.com
Subject: [PATCH] net:wireless: call cfg80211_stop_ap when switch from P2P_GO type
Date:   Thu, 28 Oct 2021 01:29:32 +0800
Message-Id: <20211027172932.774040-1-phind.uet@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

If the userspace tools switch from NL80211_IFTYPE_P2P_GO to
NL80211_IFTYPE_ADHOC via send_msg(NL80211_CMD_SET_INTERFACE), it
does not call the cleanup cfg80211_stop_ap(), this leads to the
initialization of in-use data. For example, this path re-init the
sdata->assigned_chanctx_list while it is still an element of 
assigned_vifs list, and makes that linked list corrupt.

Signed-off-by: Nguyen Dinh Phi <phind.uet@gmail.com>
Reported-by: syzbot+bbf402b783eeb6d908db@syzkaller.appspotmail.com
---
 net/wireless/util.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/wireless/util.c b/net/wireless/util.c
index 18dba3d7c638..4fdf0877092d 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -1044,6 +1044,7 @@ int cfg80211_change_iface(struct cfg80211_registered_device *rdev,
 
 		switch (otype) {
 		case NL80211_IFTYPE_AP:
+		case NL80211_IFTYPE_P2P_GO:
 			cfg80211_stop_ap(rdev, dev, true);
 			break;
 		case NL80211_IFTYPE_ADHOC:
-- 
2.25.1