4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bin Liu <b-liu@xxxxxx> commit 2b63f1329df2cd814c1f8353fae4853ace6521d1 upstream. musb_start_urb() doesn't check the pass-in parameter if it is NULL. But in musb_bulk_nak_timeout() the parameter passed to musb_start_urb() is returned from first_qh(), which could be NULL. So wrap the musb_start_urb() call here with a if condition check to avoid the potential NULL pointer dereference. Fixes: f283862f3b5c ("usb: musb: NAK timeout scheme on bulk TX endpoint") Cc: stable@xxxxxxxxxxxxxxx # v3.7+ Signed-off-by: Bin Liu <b-liu@xxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/usb/musb/musb_host.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/usb/musb/musb_host.c +++ b/drivers/usb/musb/musb_host.c @@ -1048,7 +1048,9 @@ static void musb_bulk_nak_timeout(struct /* set tx_reinit and schedule the next qh */ ep->tx_reinit = 1; } - musb_start_urb(musb, is_in, next_qh); + + if (next_qh) + musb_start_urb(musb, is_in, next_qh); } }