linux-kernel - [PATCH v1] Bluetooth: hci_uart: fix race during initialization

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <490d0026-2561-76b0-c11b-495b3e967e35@salutedevices.com>
Date: Wed, 12 Feb 2025 12:52:04 +0300
From: Arseniy Krasnov <avkrasnov@...utedevices.com>
To: Marcel Holtmann <marcel@...tmann.org>, Luiz Augusto von Dentz
	<luiz.dentz@...il.com>
CC: <oxffffaa@...il.com>, <linux-kernel@...r.kernel.org>,
	<linux-bluetooth@...r.kernel.org>, <kernel@...utedevices.com>
Subject: [PATCH v1] Bluetooth: hci_uart: fix race during initialization

Do not set 'HCI_UART_PROTO_READY' before call 'hci_uart_register_dev()'.
Possible race is when someone calls 'hci_tty_uart_close()' after this bit
is set, but 'hci_uart_register_dev()' wasn't done. This leads to access
to uninitialized fields. To fix it let's set this bit after device was
registered (as before patch c411c62cc133) and to fix previous problem let's
add one more bit in addition to 'HCI_UART_PROTO_READY' which allows to
perform power up without original bit set (pls see commit c411c62cc133).

Signed-off-by: Arseniy Krasnov <avkrasnov@...utedevices.com>
Reported-by: syzbot+683f8cb11b94b1824c77@...kaller.appspotmail.com
Closes: https://lore.kernel.org/linux-bluetooth/d159c57f-8490-4c26-79da-6ad3612c4a14@salutedevices.com/
Fixes: c411c62cc133 ("Bluetooth: hci_uart: fix race during initialization")
---
 drivers/bluetooth/hci_ldisc.c | 20 ++++++++++++++------
 drivers/bluetooth/hci_uart.h  |  1 +
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index 2651e2e33f2a1..2f322f890b81f 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -102,7 +102,8 @@ static inline struct sk_buff *hci_uart_dequeue(struct hci_uart *hu)
 	if (!skb) {
 		percpu_down_read(&hu->proto_lock);
 
-		if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
+		if (test_bit(HCI_UART_PROTO_READY, &hu->flags) ||
+		    test_bit(HCI_UART_PROTO_INIT, &hu->flags))
 			skb = hu->proto->dequeue(hu);
 
 		percpu_up_read(&hu->proto_lock);
@@ -124,7 +125,8 @@ int hci_uart_tx_wakeup(struct hci_uart *hu)
 	if (!percpu_down_read_trylock(&hu->proto_lock))
 		return 0;
 
-	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags))
+	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags) &&
+	    !test_bit(HCI_UART_PROTO_INIT, &hu->flags))
 		goto no_schedule;
 
 	set_bit(HCI_UART_TX_WAKEUP, &hu->tx_state);
@@ -278,7 +280,8 @@ static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
 
 	percpu_down_read(&hu->proto_lock);
 
-	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
+	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags) &&
+	    !test_bit(HCI_UART_PROTO_INIT, &hu->flags)) {
 		percpu_up_read(&hu->proto_lock);
 		return -EUNATCH;
 	}
@@ -585,7 +588,8 @@ static void hci_uart_tty_wakeup(struct tty_struct *tty)
 	if (tty != hu->tty)
 		return;
 
-	if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
+	if (test_bit(HCI_UART_PROTO_READY, &hu->flags) ||
+	    test_bit(HCI_UART_PROTO_INIT, &hu->flags))
 		hci_uart_tx_wakeup(hu);
 }
 
@@ -611,7 +615,8 @@ static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
 
 	percpu_down_read(&hu->proto_lock);
 
-	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
+	if (!test_bit(HCI_UART_PROTO_READY, &hu->flags) &&
+	    !test_bit(HCI_UART_PROTO_INIT, &hu->flags)) {
 		percpu_up_read(&hu->proto_lock);
 		return;
 	}
@@ -707,13 +712,16 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)
 
 	hu->proto = p;
 
-	set_bit(HCI_UART_PROTO_READY, &hu->flags);
+	set_bit(HCI_UART_PROTO_INIT, &hu->flags);
 
 	err = hci_uart_register_dev(hu);
 	if (err) {
 		return err;
 	}
 
+	set_bit(HCI_UART_PROTO_READY, &hu->flags);
+	clear_bit(HCI_UART_PROTO_INIT, &hu->flags);
+
 	return 0;
 }
 
diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
index fbf3079b92a53..5ea5dd80e297c 100644
--- a/drivers/bluetooth/hci_uart.h
+++ b/drivers/bluetooth/hci_uart.h
@@ -90,6 +90,7 @@ struct hci_uart {
 #define HCI_UART_REGISTERED		1
 #define HCI_UART_PROTO_READY		2
 #define HCI_UART_NO_SUSPEND_NOTIFIER	3
+#define HCI_UART_PROTO_INIT		4
 
 /* TX states  */
 #define HCI_UART_SENDING	1
-- 
2.30.1