diff mbox series

[PATCHv2,2/4] USB: wdm: close race between wdm_open and wdm_wwan_port_stop

Message ID 20250401084749.175246-3-oneukum@suse.com (mailing list archive)
State New
Headers show
Series USB: wdm: fix WWAN integration issue | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch

Commit Message

Oliver Neukum April 1, 2025, 8:45 a.m. UTC 
Clearing WDM_WWAN_IN_USE must be the last action or
we can open a chardev whose URBs are still poisoned

V2: added memory barriers

Fixes: cac6fb015f71 ("usb: class: cdc-wdm: WWAN framework integration")
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/usb/class/cdc-wdm.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 12038aa43942..355627982343 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -728,7 +728,7 @@  static int wdm_open(struct inode *inode, struct file *file)
 		rv = -EBUSY;
 		goto out;
 	}
-
+	smp_rmb(); /* ordered against wdm_wwan_port_stop() */
 	rv = usb_autopm_get_interface(desc->intf);
 	if (rv < 0) {
 		dev_err(&desc->intf->dev, "Error autopm - %d\n", rv);
@@ -870,8 +870,10 @@  static void wdm_wwan_port_stop(struct wwan_port *port)
 	poison_urbs(desc);
 	desc->manage_power(desc->intf, 0);
 	clear_bit(WDM_READ, &desc->flags);
-	clear_bit(WDM_WWAN_IN_USE, &desc->flags);
 	unpoison_urbs(desc);
+	smp_wmb(); /* ordered against wdm_open() */
+	/* this must be last lest we open a poisoned device */
+	clear_bit(WDM_WWAN_IN_USE, &desc->flags);
 }
 
 static void wdm_wwan_port_tx_complete(struct urb *urb)