[20/28] wifi: mac80211: mlme: fix null-ptr deref on failed assoc

Commit Message

Johannes Berg Oct. 5, 2022, 1 p.m. UTC

From: Johannes Berg <[e-mail]>

If association to an AP without a link 0 fails, then we crash in
tracing because it assumes that either ap_mld_addr or link 0 BSS
is valid, since we clear sdata->vif.valid_links and then don't
add the ap_mld_addr to the struct.

Since we clear also sdata->vif.cfg.ap_addr, keep a local copy of
it and assign it earlier, before clearing valid_links, to fix
this.

Fixes: 81151ce462e5 ("wifi: mac80211: support MLO authentication/association with one link")
Signed-off-by: Johannes Berg <[e-mail]>
---
 net/mac80211/mlme.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Patch

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index b6f378e7edea..1ad0bf3bfcae 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -5082,6 +5082,7 @@  static void ieee80211_rx_mgmt_assoc_resp(struct ieee80211_sub_if_data *sdata,
 	struct cfg80211_rx_assoc_resp resp = {
 		.uapsd_queues = -1,
 	};
+	u8 ap_mld_addr[ETH_ALEN] __aligned(2);
 	unsigned int link_id;
 
 	sdata_assert_lock(sdata);
@@ -5251,6 +5252,11 @@  static void ieee80211_rx_mgmt_assoc_resp(struct ieee80211_sub_if_data *sdata,
 				resp.uapsd_queues |= ieee80211_ac_to_qos_mask[ac];
 	}
 
+	if (sdata->vif.valid_links) {
+		ether_addr_copy(ap_mld_addr, sdata->vif.cfg.ap_addr);
+		resp.ap_mld_addr = ap_mld_addr;
+	}
+
 	ieee80211_destroy_assoc_data(sdata,
 				     status_code == WLAN_STATUS_SUCCESS ?
 					ASSOC_SUCCESS :
@@ -5260,8 +5266,6 @@  static void ieee80211_rx_mgmt_assoc_resp(struct ieee80211_sub_if_data *sdata,
 	resp.len = len;
 	resp.req_ies = ifmgd->assoc_req_ies;
 	resp.req_ies_len = ifmgd->assoc_req_ies_len;
-	if (sdata->vif.valid_links)
-		resp.ap_mld_addr = sdata->vif.cfg.ap_addr;
 	cfg80211_rx_assoc_resp(sdata->dev, &resp);
 notify_driver:
 	drv_mgd_complete_tx(sdata->local, sdata, &info);