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

Willy Tarreau
2017-06-19T18:35:14Z

From: Alexey Khoroshilov <khoroshilov@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 <khoroshilov@ispras.ru>
Acked-by: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@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