USB: cdc-acm: fix potential urb leak and PM imbalance in write

Make sure to check return value of autopm get in write() in order to
avoid urb leak and PM counter imbalance on errors.

Fixes: 11ea859d64b6 ("USB: additional power savings for cdc-acm devices
that support remote wakeup")

Cc: <stable@vger.kernel.org>	# v2.6.27
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 1ac6c5dda9f704f5fcb5276c2b635a6eb8cf3f23..c255e77282ada03e5003ce98b680a8c4b4edfa84 100644 (file)
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -668,7 +668,13 @@ static int acm_tty_write(struct tty_struct *tty,
        memcpy(wb->buf, buf, count);
        wb->len = count;
 
-       usb_autopm_get_interface_async(acm->control);
+       stat = usb_autopm_get_interface_async(acm->control);
+       if (stat) {
+               wb->use = 0;
+               spin_unlock_irqrestore(&acm->write_lock, flags);
+               return stat;
+       }
+
        if (acm->susp_count) {
                usb_anchor_urb(wb->urb, &acm->delayed);
                spin_unlock_irqrestore(&acm->write_lock, flags);