cfg80211: Fix busy loop regression in ieee80211_ie_split_ric()

This function was modified to support the information element extension case (WLAN_EID_EXTENSION) in a manner that would result in an infinite loop when going through set of IEs that include WLAN_EID_RIC_DATA and contain an IE that is in the after_ric array. The only place where this can currently happen is in mac80211 ieee80211_send_assoc() where ieee80211_ie_split_ric() is called with after_ric[].

This can be triggered by valid data from user space nl80211 association/connect request (i.e., requiring GENL_UNS_ADMIN_PERM). The only known application having an option to include WLAN_EID_RIC_DATA in these requests is wpa_supplicant and it had a bug that prevented this specific contents from being used (and because of that, not triggering this kernel bug in an automated test case ap_ft_ric) and now that this bug is fixed, it has a workaround to avoid this kernel issue. WLAN_EID_RIC_DATA is currently used only for testing purposes, so this does not cause significant harm for production use cases.

---
 net/wireless/util.c | 2 ++
 1 file changed, 2 insertions(+)

index ef14d80..d473bd1 100644
@@ -1421,6 +1421,8 @@ size_t ieee80211_ie_split_ric(const u8 *ies, size_t ielen,
 							  ies[pos + ext],
 							  ext == 2))
 					pos = skip_ie(ies, ielen, pos);
+				else
+					break;
 			}
 		} else {
 			pos = skip_ie(ies, ielen, pos);

2.7.4