wifi: mac80211: fix reporting of all valid links in sta_set_sinfo()

Currently, sta_set_sinfo() fails to populate link-level station info
when sinfo->valid_links is initially 0 and sta->sta.valid_links has
bits set for links other than link 0. This typically occurs when
association happens on a non-zero link or link 0 deleted dynamically.
In such cases, the for_each_valid_link(sinfo, link_id) loop only
executes for link 0 and terminates early, since sinfo->valid_links
remains 0. As a result, only MLD-level information is reported to
userspace.

Hence to fix, initialize sinfo->valid_links with sta->sta.valid_links
before entering the loop to ensure loop executes for each valid link.
During iteration, mask out invalid links from sinfo->valid_links if
any of sta->link[link_id], sdata->link[link_id], or sinfo->links[link_id]
are not present, to report only valid link information.

Fixes: 505991f ("wifi: mac80211: extend support to fill link level sinfo structure")
Signed-off-by: Sarika Sharma <[email protected]>
Link: https://patch.msgid.link/[email protected]
[clarify comment]
Signed-off-by: Johannes Berg <[email protected]>

Author: Sarika Sharma

net/mac80211/sta_info.c

@@ -3207,16 +3207,20 @@ void sta_set_sinfo(struct sta_info *sta, struct station_info *sinfo,
 		int link_id;
 
 		ether_addr_copy(sinfo->mld_addr, sta->addr);
+
+		/* assign valid links first for iteration */
+		sinfo->valid_links = sta->sta.valid_links;
+
 		for_each_valid_link(sinfo, link_id) {
 			link_sta = wiphy_dereference(sta->local->hw.wiphy,
 						     sta->link[link_id]);
 			link = wiphy_dereference(sdata->local->hw.wiphy,
 						 sdata->link[link_id]);
 
-			if (!link_sta || !sinfo->links[link_id] || !link)
+			if (!link_sta || !sinfo->links[link_id] || !link) {
+				sinfo->valid_links &= ~BIT(link_id);
 				continue;
-
-			sinfo->valid_links = sta->sta.valid_links;
+			}
 			sta_set_link_sinfo(sta, sinfo->links[link_id],
 					   link, tidstats);
 		}