[PATCH 3.10 052/268] USB: cdc-acm: fix open and suspend race

Willy Tarreau
2017-06-19T18:36:48Z

From: Johan Hovold <jhovold@gmail.com>

commit 703df3297fb1950b0aa53e656108eb936d3f21d9 upstream.

We must not do the usb_autopm_put_interface() before submitting the read
urbs or we might end up doing I/O to a suspended device.

Fixes: 088c64f81284 ("USB: cdc-acm: re-write read processing")
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
---
drivers/usb/class/cdc-acm.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index e16b9ef..b3ffc32 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -546,19 +546,15 @@ 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)) {
- usb_autopm_put_interface(acm->control);
goto error_set_control;
}

- usb_autopm_put_interface(acm->control);
-
/*
* Unthrottle device in case the TTY was closed while throttled.
*/
@@ -570,6 +566,8 @@ static int acm_port_activate(struct tty_port *port, struct tty_struct *tty)
if (acm_submit_read_urbs(acm, GFP_KERNEL))
goto error_submit_read_urbs;

+ usb_autopm_put_interface(acm->control);
+
mutex_unlock(&acm->mutex);

return 0;
@@ -582,6 +580,7 @@ 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