In the Linux kernel, the following vulnerability has been resolved: gfs2: Fix unlikely race in gdlmputlock In gdlmputlock(), there is a small window of time in which the DFLUNMOUNT flag has been set but the lockspace hasn't been released, yet. In that window, dlm may still call gdlmast() and gdlm_bast(). To prevent it from dereferencing freed glock objects, only free the glock if the lockspace has actually been released.