Integer signedness error in the genkbd_commonioctl function in sys/dev/kbd/kbd.c in FreeBSD 9.3 before p42 10.1 before p34 10.2 before p17 and 10.3 before p3 allows local users to obtain sensitive information from kernel memory cause a denial of service (memory overwrite and kernel crash) or gain privileges via a negative value in the flen structure member in the arg argument in a SETFKEY ioctl call which triggers a \two way heap and stack overflow.\