FST: Do not replace previous attachment

hapd->iface->fst must not be overridden if it is already pointing to FST
instance. Without this, duplicated FST-ATTACH could result in memory
leak and process termination.

Change-Id: Ib2f13d8661c8561b2bf75e821a9bd6621c10c94b
Signed-off-by: Jouni Malinen <j@w1.fi>
Git-commit: ff7a4bd13fe4a0058c5b865d390a7d57646a8d1e
Git-repo: git://w1.fi/srv/git/hostap.git
CRs-Fixed: 891455
1 file changed