[PATCH AUTOSEL 4.14 013/127] USB: serial: mos7840: fix probe error handling

Sasha Levin
2020-09-18T02:37:43Z

From: Johan Hovold <johan@kernel.org>

[ Upstream commit 960fbd1ca584a5b4cd818255769769d42bfc6dbe ]

The driver would return success and leave the port structures
half-initialised if any of the register accesses during probe fails.

This would specifically leave the port control urb unallocated,
something which could trigger a NULL pointer dereference on interrupt
events.

Fortunately the interrupt implementation is completely broken and has
never even been enabled...

Note that the zero-length-enable register write used to set the zle-flag
for all ports is moved to attach.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/usb/serial/mos7840.c | 48 +++++++++++++++++++++---------------
1 file changed, 28 insertions(+), 20 deletions(-)

diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c
index 285527f115dd7..994e2ffecbd6e 100644
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -2131,6 +2131,23 @@ static int mos7840_calc_num_ports(struct usb_serial *serial,
return num_ports;
}

+static int mos7840_attach(struct usb_serial *serial)
+{
+ struct device *dev = &serial->interface->dev;
+ int status;
+ u16 val;
+
+ /* Zero Length flag enable */
+ val = 0x0f;
+ status = mos7840_set_reg_sync(serial->port[0], ZLP_REG5, val);
+ if (status < 0)
+ dev_dbg(dev, "Writing ZLP_REG5 failed status-0x%x\n", status);
+ else
+ dev_dbg(dev, "ZLP_REG5 Writing success status%d\n", status);
+
+ return status;
+}
+
static int mos7840_port_probe(struct usb_serial_port *port)
{
struct usb_serial *serial = port->serial;
@@ -2194,7 +2211,7 @@ static int mos7840_port_probe(struct usb_serial_port *port)
mos7840_port->ControlRegOffset, &Data);
if (status < 0) {
dev_dbg(&port->dev, "Reading ControlReg failed status-0x%x\n", status);
- goto out;
+ goto error;
} else
dev_dbg(&port->dev, "ControlReg Reading success val is %x, status%d\n", Data, status);
Data |= 0x08; /* setting driver done bit */
@@ -2206,7 +2223,7 @@ static int mos7840_port_probe(struct usb_serial_port *port)
mos7840_port->ControlRegOffset, Data);
if (status < 0) {
dev_dbg(&port->dev, "Writing ControlReg failed(rx_disable) status-0x%x\n", status);
- goto out;
+ goto error;
} else
dev_dbg(&port->dev, "ControlReg Writing success(rx_disable) status%d\n", status);

@@ -2217,7 +2234,7 @@ static int mos7840_port_probe(struct usb_serial_port *port)
(__u16) (mos7840_port->DcrRegOffset + 0), Data);
if (status < 0) {
dev_dbg(&port->dev, "Writing DCR0 failed status-0x%x\n", status);
- goto out;
+ goto error;
} else
dev_dbg(&port->dev, "DCR0 Writing success status%d\n", status);

@@ -2226,7 +2243,7 @@ static int mos7840_port_probe(struct usb_serial_port *port)
(__u16) (mos7840_port->DcrRegOffset + 1), Data);
if (status < 0) {
dev_dbg(&port->dev, "Writing DCR1 failed status-0x%x\n", status);
- goto out;
+ goto error;
} else
dev_dbg(&port->dev, "DCR1 Writing success status%d\n", status);

@@ -2235,7 +2252,7 @@ static int mos7840_port_probe(struct usb_serial_port *port)
(__u16) (mos7840_port->DcrRegOffset + 2), Data);
if (status < 0) {
dev_dbg(&port->dev, "Writing DCR2 failed status-0x%x\n", status);
- goto out;
+ goto error;
} else
dev_dbg(&port->dev, "DCR2 Writing success status%d\n", status);

@@ -2244,7 +2261,7 @@ static int mos7840_port_probe(struct usb_serial_port *port)
status = mos7840_set_reg_sync(port, CLK_START_VALUE_REGISTER, Data);
if (status < 0) {
dev_dbg(&port->dev, "Writing CLK_START_VALUE_REGISTER failed status-0x%x\n", status);
- goto out;
+ goto error;
} else
dev_dbg(&port->dev, "CLK_START_VALUE_REGISTER Writing success status%d\n", status);

@@ -2261,7 +2278,7 @@ static int mos7840_port_probe(struct usb_serial_port *port)
status = mos7840_set_uart_reg(port, SCRATCH_PAD_REGISTER, Data);
if (status < 0) {
dev_dbg(&port->dev, "Writing SCRATCH_PAD_REGISTER failed status-0x%x\n", status);
- goto out;
+ goto error;
} else
dev_dbg(&port->dev, "SCRATCH_PAD_REGISTER Writing success status%d\n", status);

@@ -2275,7 +2292,7 @@ static int mos7840_port_probe(struct usb_serial_port *port)
(__u16)(ZLP_REG1 + ((__u16) mos7840_port->port_num)));
if (status < 0) {
dev_dbg(&port->dev, "Writing ZLP_REG%d failed status-0x%x\n", pnum + 2, status);
- goto out;
+ goto error;
} else
dev_dbg(&port->dev, "ZLP_REG%d Writing success status%d\n", pnum + 2, status);
} else {
@@ -2287,7 +2304,7 @@ static int mos7840_port_probe(struct usb_serial_port *port)
(__u16)(ZLP_REG1 + ((__u16) mos7840_port->port_num) - 0x1));
if (status < 0) {
dev_dbg(&port->dev, "Writing ZLP_REG%d failed status-0x%x\n", pnum + 1, status);
- goto out;
+ goto error;
} else
dev_dbg(&port->dev, "ZLP_REG%d Writing success status%d\n", pnum + 1, status);

@@ -2328,17 +2345,7 @@ static int mos7840_port_probe(struct usb_serial_port *port)
/* Turn off LED */
mos7840_set_led_sync(port, MODEM_CONTROL_REGISTER, 0x0300);
}
-out:
- if (pnum == serial->num_ports - 1) {
- /* Zero Length flag enable */
- Data = 0x0f;
- status = mos7840_set_reg_sync(serial->port[0], ZLP_REG5, Data);
- if (status < 0) {
- dev_dbg(&port->dev, "Writing ZLP_REG5 failed status-0x%x\n", status);
- goto error;
- } else
- dev_dbg(&port->dev, "ZLP_REG5 Writing success status%d\n", status);
- }
+
return 0;
error:
kfree(mos7840_port->led_dr);
@@ -2394,6 +2401,7 @@ static struct usb_serial_driver moschip7840_4port_device = {
.unthrottle = mos7840_unthrottle,
.calc_num_ports = mos7840_calc_num_ports,
.probe = mos7840_probe,
+ .attach = mos7840_attach,
.ioctl = mos7840_ioctl,
.set_termios = mos7840_set_termios,
.break_ctl = mos7840_break,
--
2.25.1