CVE-2026-15449 TOCTOU double copyin in illumos dld ioctl handling causes kernel heap corruption

A time-of-check to time-of-use TOCTOU flaw in the illumos data-link pseudo-driver dld affects handling of the DLDIOCGETMACPROP and DLDIOCSETMACPROP ioctls on /dev/dld. drviocpropcommon in usr/src/uts/common/io/dld/dlddrv.c copies the dldiocmacpropt ioctl header in once to read its prvalsize field...