5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Wentao Liang commit ef3134cd0d4831ae2137aee2883987859b80b2c6 upstream. tty_find_polling_driver() returns the tty driver with an extra reference taken by tty_driver_kref_get(). configure_kgdboc() stores it in kgdb_tty_driver but the reference is never dropped: it is leaked when kgdb_register_io_module() fails, when the configuration is cleared, and on every reconfigure. Release the reference both when unconfiguring and on the error path. Fixes: 7d7b93c1452f ("tty: kref the tty driver object") Cc: stable@kernel.org Signed-off-by: Wentao Liang Reviewed-by: Douglas Anderson Link: https://patch.msgid.link/20260917155523.2161202-1-vulab@iscas.ac.cn Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/kgdboc.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/drivers/tty/serial/kgdboc.c +++ b/drivers/tty/serial/kgdboc.c @@ -190,6 +190,11 @@ static void cleanup_kgdboc(void) return; kgdboc_unregister_kbd(); kgdb_unregister_io_module(&kgdboc_io_ops); + + if (kgdb_tty_driver) { + tty_driver_kref_put(kgdb_tty_driver); + kgdb_tty_driver = NULL; + } } static int configure_kgdboc(void) @@ -250,6 +255,10 @@ nmi_con_failed: kgdb_unregister_io_module(&kgdboc_io_ops); noconfig: kgdboc_unregister_kbd(); + if (kgdb_tty_driver) { + tty_driver_kref_put(kgdb_tty_driver); + kgdb_tty_driver = NULL; + } configured = 0; return err;