[PATCH 01/11] USB: serial: io_edgeport: fix NULL-deref on early status

[PATCH 01/11] USB: serial: io_edgeport: fix NULL-deref on early status

[Johan Hovold]

The driver submits the interrupt-in URB during probe or on first port
open, which on completion may submit the bulk-in URB before all ports
have been opened and their waitqueues have been initialised.

If a (malicious) device sends a status message for a port that has not
yet been opened this may lead to a NULL-pointer dereference in the
bulk-in completion handler when attempting to wakeup blocked tasks.

Move waitqueue initialisation from open() to port_probe() to address
this.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: syzbot+763813d65c7e18c1b6d5@syzkaller.appspotmail.com
Link: https://lore.kernel.org/6a8818d8.ae6ddae5.3da009.0031.GAE@google.com
Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/io_edgeport.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
index eaa8f00716c8..cdf41e86ba44 100644
--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -877,11 +877,6 @@ static int edge_open(struct tty_struct *tty, struct usb_serial_port *port)
 		}
 	}
 
-	/* initialize our wait queues */
-	init_waitqueue_head(&edge_port->wait_open);
-	init_waitqueue_head(&edge_port->wait_chase);
-	init_waitqueue_head(&edge_port->wait_command);
-
 	/* initialize our port settings */
 	edge_port->txCredits = 0;	/* Can't send any data yet */
 	/* Must always set this bit to enable ints! */
@@ -2965,6 +2960,11 @@ static int edge_port_probe(struct usb_serial_port *port)
 		return -ENOMEM;
 
 	spin_lock_init(&edge_port->ep_lock);
+
+	init_waitqueue_head(&edge_port->wait_open);
+	init_waitqueue_head(&edge_port->wait_chase);
+	init_waitqueue_head(&edge_port->wait_command);
+
 	edge_port->port = port;
 
 	usb_set_serial_port_data(port, edge_port);
-- 
2.55.0

[PATCH 02/11] USB: serial: io_edgeport: fix potential fifo corruption

[Johan Hovold]

The device buffer size is determined during open() and the driver
allocates a TX FIFO of corresponding size.

Add the missing sanity check to prevent memory corruption in case a
malicious device sends a second open response with a different buffer
size.

This issue was flagged by Sashiko when reviewing a related fix.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Link: https://sashiko.dev/#/patchset/20260714101316.823942-1-shpark061104%40gmail.com?part=1
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/io_edgeport.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
index cdf41e86ba44..0cc4f41299e0 100644
--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -878,7 +878,11 @@ static int edge_open(struct tty_struct *tty, struct usb_serial_port *port)
 	}
 
 	/* initialize our port settings */
+	spin_lock_irq(&edge_port->ep_lock);
 	edge_port->txCredits = 0;	/* Can't send any data yet */
+	edge_port->maxTxCredits = 0;
+	spin_unlock_irq(&edge_port->ep_lock);
+
 	/* Must always set this bit to enable ints! */
 	edge_port->shadowMCR = MCR_MASTER_IE;
 	edge_port->chaseResponsePending = false;
@@ -1750,6 +1754,7 @@ static void process_rcvd_status(struct edgeport_serial *edge_serial,
 	struct tty_struct *tty;
 	struct device *dev;
 	__u8 code = edge_serial->rxStatusCode;
+	unsigned long flags;
 
 	/* switch the port pointer to the one being currently talked about */
 	if (edge_serial->rxPort >= edge_serial->serial->num_ports)
@@ -1793,10 +1798,17 @@ static void process_rcvd_status(struct edgeport_serial *edge_serial,
 	}
 
 	if (code == IOSP_STATUS_OPEN_RSP) {
+		spin_lock_irqsave(&edge_port->ep_lock, flags);
+		/* reject stray open responses to avoid FIFO corruption */
+		if (edge_port->maxTxCredits != 0) {
+			spin_unlock_irqrestore(&edge_port->ep_lock, flags);
+			return;
+		}
 		edge_port->txCredits = GET_TX_BUFFER_SIZE(byte3);
 		edge_port->maxTxCredits = edge_port->txCredits;
 		dev_dbg(dev, "%s - Port %u Open Response Initial MSR = %02x TxBufferSize = %d\n",
 			__func__, edge_serial->rxPort, byte2, edge_port->txCredits);
+		spin_unlock_irqrestore(&edge_port->ep_lock, flags);
 		handle_new_msr(edge_port, byte2);
 
 		/* send the current line settings to the port so we are
-- 
2.55.0

[PATCH 03/11] USB: serial: io_edgeport: fix potential close() use-after-free

[Johan Hovold]

Add the missing locking when updating the port status during close() to
prevent a racing interrupt completion handler from trying to submit more
data for the port while its write URB and FIFO are being deallocated.

This issue was flagged by Sashiko when reviewing a related fix.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Link: https://sashiko.dev/#/patchset/20260714101316.823942-1-shpark061104%40gmail.com?part=1
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/io_edgeport.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
index 0cc4f41299e0..a2410c063ffe 100644
--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -1089,7 +1089,9 @@ static void edge_close(struct usb_serial_port *port)
 
 	/* port->close = true; */
 	edge_port->closePending = false;
+	spin_lock_irq(&edge_port->ep_lock);
 	edge_port->open = false;
+	spin_unlock_irq(&edge_port->ep_lock);
 	edge_port->openPending = false;
 
 	usb_kill_urb(edge_port->write_urb);
-- 
2.55.0

[PATCH 04/11] USB: serial: io_edgeport: fix potential NULL-deref at open

[Johan Hovold]

Do not mark the port as open until after the write FIFO has been
allocated and initialised to prevent a racing interrupt completion from
attempting to send stale data and dereferencing the FIFO buffer pointer.

Note that the open flag defaults to false and is cleared on close() so
there is no need to reinitialise it on every open().

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/io_edgeport.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
index a2410c063ffe..38f58ca115eb 100644
--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -889,9 +889,8 @@ static int edge_open(struct tty_struct *tty, struct usb_serial_port *port)
 
 	/* send a open port command */
 	edge_port->openPending = true;
-	edge_port->open        = false;
-	response = send_iosp_ext_cmd(edge_port, IOSP_CMD_OPEN_PORT, 0);
 
+	response = send_iosp_ext_cmd(edge_port, IOSP_CMD_OPEN_PORT, 0);
 	if (response < 0) {
 		dev_err(dev, "%s - error sending open port command\n", __func__);
 		edge_port->openPending = false;
@@ -901,8 +900,7 @@ static int edge_open(struct tty_struct *tty, struct usb_serial_port *port)
 	/* now wait for the port to be completely opened */
 	wait_event_timeout(edge_port->wait_open, !edge_port->openPending,
 								OPEN_TIMEOUT);
-
-	if (!edge_port->open) {
+	if (edge_port->openPending) {
 		/* open timed out */
 		dev_dbg(dev, "%s - open timeout\n", __func__);
 		edge_port->openPending = false;
@@ -930,6 +928,10 @@ static int edge_open(struct tty_struct *tty, struct usb_serial_port *port)
 		return -ENOMEM;
 	}
 
+	spin_lock_irq(&edge_port->ep_lock);
+	edge_port->open = true;
+	spin_unlock_irq(&edge_port->ep_lock);
+
 	dev_dbg(dev, "%s - Initialize TX fifo to %d bytes\n",
 		__func__, edge_port->maxTxCredits);
 
@@ -1092,7 +1094,6 @@ static void edge_close(struct usb_serial_port *port)
 	spin_lock_irq(&edge_port->ep_lock);
 	edge_port->open = false;
 	spin_unlock_irq(&edge_port->ep_lock);
-	edge_port->openPending = false;
 
 	usb_kill_urb(edge_port->write_urb);
 
@@ -1824,7 +1825,6 @@ static void process_rcvd_status(struct edgeport_serial *edge_serial,
 
 		/* we have completed the open */
 		edge_port->openPending = false;
-		edge_port->open = true;
 		wake_up(&edge_port->wait_open);
 		return;
 	}
-- 
2.55.0

[PATCH 05/11] USB: serial: io_edgeport: serialise MCR accesses

[Johan Hovold]

Add a mutex to serialise modem control register updates to prevent
concurrent tasks from interfering with each other.

Note that the register updates are currently asynchronous so a task may
read back a value which has not yet taken effect.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
---
 drivers/usb/serial/io_edgeport.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
index 38f58ca115eb..0b50c6b99b0a 100644
--- a/drivers/usb/serial/io_edgeport.c
+++ b/drivers/usb/serial/io_edgeport.c
@@ -168,6 +168,7 @@ struct edgeport_port {
 	struct urb		*write_urb;		/* write URB for this port */
 	bool			write_in_progress;	/* 'true' while a write URB is outstanding */
 	spinlock_t		ep_lock;
+	struct mutex		mutex;
 
 	__u8			shadowLCR;		/* last LCR value received */
 	__u8			shadowMCR;		/* last MCR value received */
@@ -884,7 +885,10 @@ static int edge_open(struct tty_struct *tty, struct usb_serial_port *port)
 	spin_unlock_irq(&edge_port->ep_lock);
 
 	/* Must always set this bit to enable ints! */
+	mutex_lock(&edge_port->mutex);
 	edge_port->shadowMCR = MCR_MASTER_IE;
+	mutex_unlock(&edge_port->mutex);
+
 	edge_port->chaseResponsePending = false;
 
 	/* send a open port command */
@@ -1397,9 +1401,11 @@ static void edge_throttle(struct tty_struct *tty)
 
 	/* if we are implementing RTS/CTS, toggle that line */
 	if (C_CRTSCTS(tty)) {
+		mutex_lock(&edge_port->mutex);
 		edge_port->shadowMCR &= ~MCR_RTS;
 		status = send_cmd_write_uart_register(edge_port, MCR,
 							edge_port->shadowMCR);
+		mutex_unlock(&edge_port->mutex);
 		if (status != 0)
 			return;
 	}
@@ -1434,9 +1440,11 @@ static void edge_unthrottle(struct tty_struct *tty)
 	}
 	/* if we are implementing RTS/CTS, toggle that line */
 	if (C_CRTSCTS(tty)) {
+		mutex_lock(&edge_port->mutex);
 		edge_port->shadowMCR |= MCR_RTS;
 		send_cmd_write_uart_register(edge_port, MCR,
 						edge_port->shadowMCR);
+		mutex_unlock(&edge_port->mutex);
 	}
 }
 
@@ -1501,6 +1509,7 @@ static int edge_tiocmset(struct tty_struct *tty,
 	struct edgeport_port *edge_port = usb_get_serial_port_data(port);
 	unsigned int mcr;
 
+	mutex_lock(&edge_port->mutex);
 	mcr = edge_port->shadowMCR;
 	if (set & TIOCM_RTS)
 		mcr |= MCR_RTS;
@@ -1519,6 +1528,7 @@ static int edge_tiocmset(struct tty_struct *tty,
 	edge_port->shadowMCR = mcr;
 
 	send_cmd_write_uart_register(edge_port, MCR, edge_port->shadowMCR);
+	mutex_unlock(&edge_port->mutex);
 
 	return 0;
 }
@@ -1532,6 +1542,7 @@ static int edge_tiocmget(struct tty_struct *tty)
 	unsigned int mcr;
 
 	msr = edge_port->shadowMSR;
+	mutex_lock(&edge_port->mutex);
 	mcr = edge_port->shadowMCR;
 	result = ((mcr & MCR_DTR)	? TIOCM_DTR: 0)	  /* 0x002 */
 		  | ((mcr & MCR_RTS)	? TIOCM_RTS: 0)   /* 0x004 */
@@ -1539,6 +1550,7 @@ static int edge_tiocmget(struct tty_struct *tty)
 		  | ((msr & EDGEPORT_MSR_CD)	? TIOCM_CAR: 0)   /* 0x040 */
 		  | ((msr & EDGEPORT_MSR_RI)	? TIOCM_RI:  0)   /* 0x080 */
 		  | ((msr & EDGEPORT_MSR_DSR)	? TIOCM_DSR: 0);  /* 0x100 */
+	mutex_unlock(&edge_port->mutex);
 
 	return result;
 }
@@ -2477,12 +2489,14 @@ static void change_port_settings(struct tty_struct *tty,
 		return;
 
 	/* set up the MCR register and send it to the EdgePort */
+	mutex_lock(&edge_port->mutex);
 	edge_port->shadowMCR = MCR_MASTER_IE;
 	if (cflag & CBAUD)
 		edge_port->shadowMCR |= (MCR_DTR | MCR_RTS);
 
 	status = send_cmd_write_uart_register(edge_port, MCR,
 						edge_port->shadowMCR);
+	mutex_unlock(&edge_port->mutex);
 	if (status != 0)
 		return;
 
@@ -2974,6 +2988,7 @@ static int edge_port_probe(struct usb_serial_port *port)
 		return -ENOMEM;
 
 	spin_lock_init(&edge_port->ep_lock);
+	mutex_init(&edge_port->mutex);
 
 	init_waitqueue_head(&edge_port->wait_open);
 	init_waitqueue_head(&edge_port->wait_chase);
-- 
2.55.0