Re: [syzbot] test uaf in hci_conn_drop

[syzbot <syzbot+1683f76f1b20b826de67@syzkaller.appspotmail.com>]

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Subject: test uaf in hci_conn_drop
Author: lizhi.xu@windriver.com

#syz test git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git 8de1e7afcc1c

diff --git a/net/bluetooth/hci_sysfs.c b/net/bluetooth/hci_sysfs.c
index 15b33579007c..3c6592da21c4 100644
--- a/net/bluetooth/hci_sysfs.c
+++ b/net/bluetooth/hci_sysfs.c
@@ -6,6 +6,8 @@
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci_core.h>
 
+static void sco_set_hci_cnn_null(struct hci_conn * conn);
+
 static const struct class bt_class = {
 	.name = "bluetooth",
 };
@@ -13,6 +15,7 @@ static const struct class bt_class = {
 static void bt_link_release(struct device *dev)
 {
 	struct hci_conn *conn = to_hci_conn(dev);
+	sco_set_hci_cnn_null(conn);
 	kfree(conn);
 }
 
diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index c736186aba26..6c3b1ee78ba8 100644
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -76,6 +76,12 @@ struct sco_pinfo {
 #define SCO_CONN_TIMEOUT	(HZ * 40)
 #define SCO_DISCONN_TIMEOUT	(HZ * 2)
 
+static void sco_set_hci_cnn_null(struct hci_conn * conn)
+{
+	struct sco_conn * scn = container_of(conn, struct sco_conn, hcon);
+	scn->hcon = NULL;
+}
+
 static void sco_sock_timeout(struct work_struct *work)
 {
 	struct sco_conn *conn = container_of(work, struct sco_conn,