[PATCH] usb: cdns3: fix use-after-free in cdns3_gadget_exit()

[Fan Wu]

cdns3_gadget_start() arms two works on system_freezable_wq:
pending_status_wq for the deferred ep0 status stage and aligned_buf_wq
for realigned request buffers. Both handlers use the cdns3_device the
works are embedded in, and cdns3_pending_setup_status_handler() also
calls the ep0 request completion.

cdns3_gadget_exit() does not wait for these works. It frees all
endpoints and aligned buffers and drops the last reference to the
gadget device, which frees priv_dev, so a work queued before the exit
can run after the free.

Fix this by waiting for both works after the gadget driver is unbound
and the IRQ is freed, when no new work can be queued, and before the
endpoints and buffers are released.

This issue was found by an in-house static analysis tool.

Fixes: 7733f6c32e36 ("usb: cdns3: Add Cadence USB3 DRD Driver")
Cc: stable@xxxxxxxxxxxxxxx
Reported-by: Sicong Huang <congei42@xxxxxxx>
Closes: https://lore.kernel.org/linux-usb/7f5719b.8700.18f67b324d3.Coremail.congei42@xxxxxxx/
Suggested-by: Sicong Huang <congei42@xxxxxxx>
Assisted-by: Codex:gpt-5.6
Co-developed-by: Song Li <songl@xxxxxxxxxx>
Signed-off-by: Song Li <songl@xxxxxxxxxx>
Signed-off-by: Fan Wu <fanwu01@xxxxxxxxxx>
---
 drivers/usb/cdns3/cdns3-gadget.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/cdns3/cdns3-gadget.c b/drivers/usb/cdns3/cdns3-gadget.c
index 42311c1bf..0d272e9c5 100644
--- a/drivers/usb/cdns3/cdns3-gadget.c
+++ b/drivers/usb/cdns3/cdns3-gadget.c
@@ -3269,6 +3269,10 @@ static void cdns3_gadget_exit(struct cdns *cdns)
 	usb_del_gadget(&priv_dev->gadget);
 	devm_free_irq(cdns->dev, cdns->dev_irq, priv_dev);
 
+	/* The works can still be queued until the IRQ is freed. */
+	cancel_work_sync(&priv_dev->pending_status_wq);
+	cancel_work_sync(&priv_dev->aligned_buf_wq);
+
 	cdns3_free_all_eps(priv_dev);
 
 	while (!list_empty(&priv_dev->aligned_buf_list)) {