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commitf6c7bc4a68upstream. This reverts commitffd603f214. Commitffd603f214("usb: gadget: u_serial: Add null pointer check in gs_start_io") adds null pointer checks at the beginning of the gs_start_io() function to prevent a null pointer dereference. However, these checks are redundant because the function's comment already requires callers to hold the port_lock and ensure port.tty and port_usb are not null. All existing callers already follow these rules. The true cause of the null pointer dereference is a race condition. When gs_start_io() calls either gs_start_rx() or gs_start_tx(), the port_lock is temporarily released for usb_ep_queue(). This allows port.tty and port_usb to be cleared. Fixes:ffd603f214("usb: gadget: u_serial: Add null pointer check in gs_start_io") 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/r/20250617050844.1848232-1-khtsai@google.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>