7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Igor Putko commit 810d467c11f0c85107874d08dfdd11acba6aa0c0 upstream. When a serial port configured as a console is opened and subsequently closed, tty_port_shutdown() skips invoking port->ops->shutdown() because port->console is true. As a result, tty_port_initialized() remains true and the port's interrupt handler stays registered in the irq subsystem. If the underlying device is later unbound or removed (e.g. via sysfs driver unbind or device hot-unplug), serial_core_remove_one_port() unregisters the console, frees uport->name via kfree(), and tears down the port without shutting it down or freeing its IRQ. Consequently, the irqaction descriptor remains registered in genirq with action->name pointing to freed memory. This triggers a use-after-free read whenever genirq accesses action->name, such as when reading /proc/interrupts: BUG: KASAN: slab-use-after-free in string+0x476/0x570 Call Trace: string+0x476/0x570 vsnprintf+0x422/0x1300 seq_printf+0x... show_interrupts+... Fix this by acquiring port->mutex in serial_core_remove_one_port() after console unregistration, clearing port->console under the mutex to prevent data races with concurrent tty_port_shutdown(), and invoking uart_shutdown(NULL, state) if the port remains initialized. This ensures that port->ops->shutdown() is called and the IRQ is freed before kfree(uport->name). Reported-by: syzbot+843bf2f48f4d12e6682e@syzkaller.appspotmail.com Cc: stable Closes: https://syzkaller.appspot.com/bug?extid=843bf2f48f4d12e6682e Fixes: 761ed4a94582 ("tty: serial_core: convert uart_close to use tty_port_close") Fixes: f7048b15900f ("tty: serial_core: Add name field to uart_port struct") Signed-off-by: Igor Putko Link: https://patch.msgid.link/20261003163337.45577-1-igorpetindev@gmail.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/serial_core.c | 7 +++++++ 1 file changed, 7 insertions(+) --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -3241,6 +3241,13 @@ static void serial_core_remove_one_port( if (uart_console(uport)) unregister_console(uport->cons); + scoped_guard(mutex, &port->mutex) { + port->console = false; + + if (tty_port_initialized(port)) + uart_shutdown(NULL, state); + } + /* * Free the port IO and memory resources, if any. */