[PATCH 3.10 051/268] USB: cdc-acm: fix double usb_autopm_put_interface() in acm_port_activate()

[Willy Tarreau]

From: Alexey Khoroshilov <khoroshi...@ispras.ru>

commit 070c0b17f6a1ba39dff9be112218127e7e8fd456 upstream.

If acm_submit_read_urbs() fails in acm_port_activate(), error handling
code calls usb_autopm_put_interface() while it is already called
before acm_submit_read_urbs(). The patch reorganizes error handling code
to avoid double decrement of USB interface's PM-usage counter.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshi...@ispras.ru>
Acked-by: Oliver Neukum <oli...@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Signed-off-by: Willy Tarreau <w...@1wt.eu>
---
 drivers/usb/class/cdc-acm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index b364845..e16b9ef 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -546,13 +546,16 @@ static int acm_port_activate(struct tty_port *port, 
struct tty_struct *tty)
        if (usb_submit_urb(acm->ctrlurb, GFP_KERNEL)) {
                dev_err(&acm->control->dev,
                        "%s - usb_submit_urb(ctrl irq) failed\n", __func__);
+               usb_autopm_put_interface(acm->control);
                goto error_submit_urb;
        }
 
        acm->ctrlout = ACM_CTRL_DTR | ACM_CTRL_RTS;
        if (acm_set_control(acm, acm->ctrlout) < 0 &&
-           (acm->ctrl_caps & USB_CDC_CAP_LINE))
+           (acm->ctrl_caps & USB_CDC_CAP_LINE)) {
+               usb_autopm_put_interface(acm->control);
                goto error_set_control;
+       }
 
        usb_autopm_put_interface(acm->control);
 
@@ -579,7 +582,6 @@ error_submit_read_urbs:
 error_set_control:
        usb_kill_urb(acm->ctrlurb);
 error_submit_urb:
-       usb_autopm_put_interface(acm->control);
 error_get_interface:
 disconnected:
        mutex_unlock(&acm->mutex);
-- 
2.8.0.rc2.1.gbe9624a