usb: gadget: f_hid: move list and spinlock inits from bind to alloc

[ Upstream commit 4e0a88254ad59f6c53a34bf5fa241884ec09e8b2 ]

There was an issue when you did the following:
- setup and bind an hid gadget
- open /dev/hidg0
- use the resulting fd in EPOLL_CTL_ADD
- unbind the UDC
- bind the UDC
- use the fd in EPOLL_CTL_DEL

When CONFIG_DEBUG_LIST was enabled, a list_del corruption was reported
within remove_wait_queue (via ep_remove_wait_queue). After some
debugging I found out that the queues, which f_hid registers via
poll_wait were the problem. These were initialized using
init_waitqueue_head inside hidg_bind. So effectively, the bind function
re-initialized the queues while there were still items in them.

The solution is to move the initialization from hidg_bind to hidg_alloc
to extend their lifetimes to the lifetime of the function instance.

Additionally, I found many other possibly problematic init calls in the
bind function, which I moved as well.

Signed-off-by: Michael Zimmermann <sigmaepsilon92@gmail.com>
Cc: stable <stable@kernel.org>
Link: https://patch.msgid.link/20260331184844.2388761-1-sigmaepsilon92@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c
index c20d3426571ec5ff5d3ca36fc17e422385818571..de00785fa183dfe177f408d1989551b3561ea778 100644 (file)
--- a/drivers/usb/gadget/function/f_hid.c
+++ b/drivers/usb/gadget/function/f_hid.c
@@ -996,13 +996,8 @@ static int hidg_bind(struct usb_configuration *c, struct usb_function *f)
        if (status)
                goto fail;
 
-       spin_lock_init(&hidg->write_spinlock);
        hidg->write_pending = 1;
        hidg->req = NULL;
-       spin_lock_init(&hidg->read_spinlock);
-       init_waitqueue_head(&hidg->write_queue);
-       init_waitqueue_head(&hidg->read_queue);
-       INIT_LIST_HEAD(&hidg->completed_out_req);
 
        /* create char device */
        cdev_init(&hidg->cdev, &f_hidg_fops);
@@ -1272,6 +1267,12 @@ static struct usb_function *hidg_alloc(struct usb_function_instance *fi)
        mutex_lock(&opts->lock);
        ++opts->refcnt;
 
+       spin_lock_init(&hidg->write_spinlock);
+       spin_lock_init(&hidg->read_spinlock);
+       init_waitqueue_head(&hidg->write_queue);
+       init_waitqueue_head(&hidg->read_queue);
+       INIT_LIST_HEAD(&hidg->completed_out_req);
+
        device_initialize(&hidg->dev);
        hidg->dev.release = hidg_release;
        hidg->dev.class = hidg_class;