Re: [syzbot] [wireless?] UBSAN: array-index-out-of-bounds in ieee80211_request_ibss_scan

[Edward Adam Davis <eadavis@qq.com>]

#syz test

diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index cb7079071885..88ee1ce44e8e 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -369,6 +369,9 @@ static bool ieee80211_prep_hw_scan(struct ieee80211_sub_if_data *sdata)
 		return false;
 
 	if (ieee80211_hw_check(&local->hw, SINGLE_SCAN_ON_ALL_BANDS)) {
+		if (WARN_ON_ONCE(req->n_channels == 0))
+			return -EINVAL;
+
 		local->hw_scan_req->req.n_channels = req->n_channels;
 
 		for (i = 0; i < req->n_channels; i++) {
@@ -760,6 +763,9 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 		/* None of the channels are actually set
 		 * up but let UBSAN know the boundaries.
 		 */
+		if (WARN_ON_ONCE(req->n_channels == 0))
+			return -EINVAL;
+
 		local->hw_scan_req->req.n_channels = req->n_channels;
 
 		ies = (u8 *)local->hw_scan_req +