A NULL pointer dereference was found in iofilebitmapget in iouring/filetable.c in the iouring sub-component in the Linux Kernel. When fixed files are unregistered, some context information (filealloc{start,end} and allochint) is not cleared. A subsequent request that has auto index selection enabled via IORINGFILEINDEX_ALLOC can cause a NULL pointer dereference. An unprivileged user can use the flaw to cause a system crash.