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Kuen-Han Tsai
ee8d688e2b
commitc529c3730bupstream. A race condition occurs when gs_start_io() calls either gs_start_rx() or gs_start_tx(), as those functions briefly drop the port_lock for usb_ep_queue(). This allows gs_close() and gserial_disconnect() to clear port.tty and port_usb, respectively. Use the null-safe TTY Port helper function to wake up TTY. Example CPU1: CPU2: gserial_connect() // lock gs_close() // await lock gs_start_rx() // unlock usb_ep_queue() gs_close() // lock, reset port.tty and unlock gs_start_rx() // lock tty_wakeup() // NPE Fixes:35f95fd7f2("TTY: usb/u_serial, use tty from tty_port") Cc: stable <stable@kernel.org> Signed-off-by: Kuen-Han Tsai <khtsai@google.com> Reviewed-by: Prashanth K <prashanth.k@oss.qualcomm.com> Link: https://lore.kernel.org/linux-usb/20240116141801.396398-1-khtsai@google.com/ Link: https://lore.kernel.org/r/20250617050844.1848232-2-khtsai@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>