wifi: mac80211: mesh: check element parsing succeeded

ieee802_11_parse_elems() can return NULL, so we must
check for the return value.

Fixes: 5d24828d ("mac80211: always allocate struct ieee802_11_elems")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20231211085121.93dea364f3d3.Ie87781c6c48979fb25a744b90af4a33dc2d83a28@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mesh_plink.c

@@ -1247,6 +1247,8 @@ void mesh_rx_plink_frame(struct ieee80211_sub_if_data *sdata,
 			return;
 	}
 	elems = ieee802_11_parse_elems(baseaddr, len - baselen, true, NULL);
+	if (elems) {
 		mesh_process_plink_frame(sdata, mgmt, elems, rx_status);
 		kfree(elems);
+	}
 }