The function ieee80211_ie_split_vendor doesn't return 0 on errors. Instead
it returns any offset < ielen when WLAN_EID_VENDOR_SPECIFIC is found. The
return value in mesh_add_vendor_ies must therefore be checked against
ifmsh->ie_len and not 0. Otherwise all ifmsh->ie starting with
WLAN_EID_VENDOR_SPECIFIC will be rejected.

Fixes: 082ebb0c ("mac80211: fix mesh beacon format")
Signed-off-by: NThorsten Horstmann <thorsten@defutech.de>
Signed-off-by: NMathias Kretschmer <mathias.kretschmer@fit.fraunhofer.de>
Signed-off-by: NSimon Wunderlich <sw@simonwunderlich.de>
[sven@narfation.org: Add commit message]
Signed-off-by: NSven Eckelmann <sven@narfation.org>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>