mac80211: make ieee80211_build_preq_ies safer

Instead of assuming 200 bytes are always enough for
all the IEs we add, give the length of the buffer
to the function and warn instead of overrunning.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

1 files changed, 12 insertions, 9 deletions

diff --git a/net/mac80211/scan.c b/net/mac80211/scan.c
index ddd1a9aaff3..d7c190b8067 100644
--- a/net/mac80211/scan.c
+++ b/net/mac80211/scan.c
@@ -247,6 +247,7 @@ static bool ieee80211_prep_hw_scan(struct ieee80211_local *local)
 	local->hw_scan_req->n_channels = n_chans;
 
 	ielen = ieee80211_build_preq_ies(local, (u8 *)local->hw_scan_req->ie,
+					 local->hw_scan_ies_bufsize,
 					 req->ie, req->ie_len, band,
 					 req->rates[band], 0);
 	local->hw_scan_req->ie_len = ielen;
@@ -445,11 +446,13 @@ static int __ieee80211_start_scan(struct ieee80211_sub_if_data *sdata,
 	if (local->ops->hw_scan) {
 		u8 *ies;
 
+		local->hw_scan_ies_bufsize = 2 + IEEE80211_MAX_SSID_LEN +
+					     local->scan_ies_len +
+					     req->ie_len;
 		local->hw_scan_req = kmalloc(
 				sizeof(*local->hw_scan_req) +
 				req->n_channels * sizeof(req->channels[0]) +
-				2 + IEEE80211_MAX_SSID_LEN + local->scan_ies_len +
-				req->ie_len, GFP_KERNEL);
+				local->hw_scan_ies_bufsize, GFP_KERNEL);
 		if (!local->hw_scan_req)
 			return -ENOMEM;
 
@@ -928,7 +931,10 @@ int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_sched_scan_ies sched_scan_ies;
-	int ret, i;
+	int ret, i, iebufsz;
+
+	iebufsz = 2 + IEEE80211_MAX_SSID_LEN +
+		  local->scan_ies_len + req->ie_len;
 
 	mutex_lock(&local->mtx);
 
@@ -946,10 +952,7 @@ int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
 		if (!local->hw.wiphy->bands[i])
 			continue;
 
-		sched_scan_ies.ie[i] = kzalloc(2 + IEEE80211_MAX_SSID_LEN +
-					       local->scan_ies_len +
-					       req->ie_len,
-					       GFP_KERNEL);
+		sched_scan_ies.ie[i] = kzalloc(iebufsz, GFP_KERNEL);
 		if (!sched_scan_ies.ie[i]) {
 			ret = -ENOMEM;
 			goto out_free;
@@ -957,8 +960,8 @@ int ieee80211_request_sched_scan_start(struct ieee80211_sub_if_data *sdata,
 
 		sched_scan_ies.len[i] =
 			ieee80211_build_preq_ies(local, sched_scan_ies.ie[i],
-						 req->ie, req->ie_len, i,
-						 (u32) -1, 0);
+						 iebufsz, req->ie, req->ie_len,
+						 i, (u32) -1, 0);
 	}
 
 	ret = drv_sched_scan_start(local, sdata, req, &sched_scan_ies);