USB: mos7840: fix race in register handling
Fix race in mos7840_get_reg which unconditionally manipulated the
control urb (which may already be in use) by adding a control-urb busy
flag.
Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c
index 603fb70..73dda1c 100644
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -183,6 +183,10 @@
#define LED_ON_MS 500
#define LED_OFF_MS 500
+enum mos7840_flag {
+ MOS7840_FLAG_CTRL_BUSY,
+};
+
static int device_type;
static const struct usb_device_id id_table[] = {
@@ -241,6 +245,8 @@
bool led_flag;
struct timer_list led_timer1; /* Timer for LED on */
struct timer_list led_timer2; /* Timer for LED off */
+
+ unsigned long flags;
};
/*
@@ -460,10 +466,10 @@
case -ESHUTDOWN:
/* this urb is terminated, clean up */
dev_dbg(dev, "%s - urb shutting down with status: %d\n", __func__, status);
- return;
+ goto out;
default:
dev_dbg(dev, "%s - nonzero urb status received: %d\n", __func__, status);
- return;
+ goto out;
}
dev_dbg(dev, "%s urb buffer size is %d\n", __func__, urb->actual_length);
@@ -476,6 +482,8 @@
mos7840_handle_new_msr(mos7840_port, regval);
else if (mos7840_port->MsrLsr == 1)
mos7840_handle_new_lsr(mos7840_port, regval);
+out:
+ clear_bit_unlock(MOS7840_FLAG_CTRL_BUSY, &mos7840_port->flags);
}
static int mos7840_get_reg(struct moschip_port *mcs, __u16 Wval, __u16 reg,
@@ -486,6 +494,9 @@
unsigned char *buffer = mcs->ctrl_buf;
int ret;
+ if (test_and_set_bit_lock(MOS7840_FLAG_CTRL_BUSY, &mcs->flags))
+ return -EBUSY;
+
dr->bRequestType = MCS_RD_RTYPE;
dr->bRequest = MCS_RDREQ;
dr->wValue = cpu_to_le16(Wval); /* 0 */
@@ -497,6 +508,9 @@
mos7840_control_callback, mcs);
mcs->control_urb->transfer_buffer_length = 2;
ret = usb_submit_urb(mcs->control_urb, GFP_ATOMIC);
+ if (ret)
+ clear_bit_unlock(MOS7840_FLAG_CTRL_BUSY, &mcs->flags);
+
return ret;
}