linux-kernel - [PATCH] media: ttusbir: fix race between device disconnection and urb callback

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Message-ID: <20251114101418.2548-1-vulab@iscas.ac.cn>
Date: Fri, 14 Nov 2025 18:14:18 +0800
From: Haotian Zhang <vulab@...as.ac.cn>
To: sean@...s.org,
	mchehab@...nel.org
Cc: linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Haotian Zhang <vulab@...as.ac.cn>
Subject: [PATCH] media: ttusbir: fix race between device disconnection and urb callback

The ttusbir_disconnect() function calls rc_unregister_device() before
usb_kill_urb(), creating a race condition similar to the one fixed in
commit 'f656cfbc7a29'. If rc_unregister_device() executes while
the URB callback ttusbir_urb_complete() is still running,
ttusbir_process_ir_data() may call ir_raw_event_store_with_filter()
or ir_raw_event_handle() with a freed tt->rc->raw pointer, leading to
a NULL pointer dereference.

Call usb_kill_urb() before rc_unregister_device() to ensure all URB
callbacks complete before freeing device resources.

Fixes: 0938069fa089 ("[media] rc: Add support for the TechnoTrend USB IR Receiver")
Signed-off-by: Haotian Zhang <vulab@...as.ac.cn>
---
 drivers/media/rc/ttusbir.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/rc/ttusbir.c b/drivers/media/rc/ttusbir.c
index 560a26f3965c..c1fbbc03dd29 100644
--- a/drivers/media/rc/ttusbir.c
+++ b/drivers/media/rc/ttusbir.c
@@ -363,7 +363,6 @@ static void ttusbir_disconnect(struct usb_interface *intf)

 	tt->udev = NULL;

-	rc_unregister_device(tt->rc);
 	led_classdev_unregister(&tt->led);
 	for (i = 0; i < NUM_URBS; i++) {
 		usb_kill_urb(tt->urb[i]);
@@ -372,6 +371,7 @@ static void ttusbir_disconnect(struct usb_interface *intf)
 		usb_free_urb(tt->urb[i]);
 	}
 	usb_kill_urb(tt->bulk_urb);
+	rc_unregister_device(tt->rc);
 	usb_free_urb(tt->bulk_urb);
 	usb_set_intfdata(intf, NULL);
 	kfree(tt);
-- 
2.50.1.windows.1