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   1 From: Felix Fietkau <nbd@nbd.name>
   2 Date: Fri, 15 Nov 2024 12:28:43 +0100
   3 Subject: [PATCH] wifi: mac80211: fix vif addr when switching from monitor
   4  to station
   5
   6 Since adding support for opting out of virtual monitor support, a zero vif
   7 addr was used to indicate passive vs active monitor to the driver.
   8 This would break the vif->addr when changing the netdev mac address before
   9 switching the interface from monitor to sta mode.
  10 Fix the regression by adding a separate flag to indicate whether vif->addr
  11 is valid.
  12
  13 Reported-by: syzbot+9ea265d998de25ac6a46@syzkaller.appspotmail.com
  14 Fixes: 9d40f7e32774 ("wifi: mac80211: add flag to opt out of virtual monitor support")
  15 Signed-off-by: Felix Fietkau <nbd@nbd.name>
  16 ---
  17
  18 --- a/include/net/mac80211.h
  19 +++ b/include/net/mac80211.h
  20 @@ -1972,6 +1972,8 @@ enum ieee80211_neg_ttlm_res {
  21   * @neg_ttlm: negotiated TID to link mapping info.
  22   *     see &struct ieee80211_neg_ttlm.
  23   * @addr: address of this interface
  24 + * @addr_valid: indicates if the address is actively used. Set to false for
  25 + *     passive monitor interfaces, true in all other cases.
  26   * @p2p: indicates whether this AP or STA interface is a p2p
  27   *     interface, i.e. a GO or p2p-sta respectively
  28   * @netdev_features: tx netdev features supported by the hardware for this
  29 @@ -2011,6 +2013,7 @@ struct ieee80211_vif {
  30         u16 valid_links, active_links, dormant_links, suspended_links;
  31         struct ieee80211_neg_ttlm neg_ttlm;
  32         u8 addr[ETH_ALEN] __aligned(2);
  33 +       bool addr_valid;
  34         bool p2p;
  35
  36         u8 cab_queue;
  37 --- a/net/mac80211/iface.c
  38 +++ b/net/mac80211/iface.c
  39 @@ -279,13 +279,8 @@ static int _ieee80211_change_mac(struct
  40         ret = eth_mac_addr(sdata->dev, sa);
  41
  42         if (ret == 0) {
  43 -               if (check_dup) {
  44 -                       memcpy(sdata->vif.addr, sa->sa_data, ETH_ALEN);
  45 -                       ether_addr_copy(sdata->vif.bss_conf.addr, sdata->vif.addr);
  46 -               } else {
  47 -                       memset(sdata->vif.addr, 0, ETH_ALEN);
  48 -                       memset(sdata->vif.bss_conf.addr, 0, ETH_ALEN);
  49 -               }
  50 +               memcpy(sdata->vif.addr, sa->sa_data, ETH_ALEN);
  51 +               ether_addr_copy(sdata->vif.bss_conf.addr, sdata->vif.addr);
  52         }
  53
  54         /* Regardless of eth_mac_addr() return we still want to add the
  55 @@ -1324,6 +1319,8 @@ int ieee80211_do_open(struct wireless_de
  56                 }
  57         }
  58
  59 +       sdata->vif.addr_valid = sdata->vif.type != NL80211_IFTYPE_MONITOR ||
  60 +                               (sdata->u.mntr.flags & MONITOR_FLAG_ACTIVE);
  61         switch (sdata->vif.type) {
  62         case NL80211_IFTYPE_AP_VLAN:
  63                 /* no need to tell driver, but set carrier and chanctx */