From a916fa66a43e10f63198b6ce978badffc678821a Mon Sep 17 00:00:00 2001 From: Lucas De Marchi Date: Thu, 6 Aug 2026 17:21:03 +0300 Subject: [PATCH] xhci: dbgtty: Fix unregister on tty_register_driver() failure If tty_register_driver() fails, it drops the reference, but fails to set the global dbc_tty_driver to NULL, causing the unregister to be called again when module exits. On module unload dbc_tty_exit() only gates its cleanup on the driver pointer being non-NULL, so it operates on the already-freed driver: module_init(xhci_hcd_init) xhci_hcd_init() xhci_dbc_init() [return value ignored] dbc_tty_init() tty_register_driver() fails tty_driver_kref_put() -> driver freed (dbc_tty_driver left dangling) ... module_exit(xhci_hcd_fini) xhci_hcd_fini() xhci_dbc_exit() dbc_tty_exit() if (dbc_tty_driver) -> true (dangling) tty_unregister_driver() -> use-after-free Fixes: 4521f1613940 ("xhci: dbctty: split dbc tty driver registration and unregistration functions.") Cc: stable@vger.kernel.org # v5.10 Cc: Mathias Nyman Cc: Greg Kroah-Hartman Signed-off-by: Lucas De Marchi Signed-off-by: Mathias Nyman Link: https://patch.msgid.link/20260806142113.2436238-8-mathias.nyman@linux.intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/xhci-dbgtty.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/usb/host/xhci-dbgtty.c b/drivers/usb/host/xhci-dbgtty.c index 2e7384c6b6ec..01decd46f313 100644 --- a/drivers/usb/host/xhci-dbgtty.c +++ b/drivers/usb/host/xhci-dbgtty.c @@ -651,6 +651,7 @@ int dbc_tty_init(void) pr_err("Can't register dbc tty driver\n"); tty_driver_kref_put(dbc_tty_driver); idr_destroy(&dbc_tty_minors); + dbc_tty_driver = NULL; } return ret;