nl80211: fix radio statistics in survey dump

Even if userspace specifies the NL80211_ATTR_SURVEY_RADIO_STATS
attribute, we cannot get the statistics because we're not really
parsing the incoming attributes properly any more.

Fix this by passing the attrbuf to nl80211_prepare_wdev_dump()
and filling it there, if given, and using a local version only
if no output is desired.

Since I'm touching it anyway, make nl80211_prepare_wdev_dump()
static.

Fixes: 50508d941c18 ("cfg80211: use parallel_ops for genl")
Reported-by: Jan Fuchs <jf@simonwunderlich.de>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Tested-by: Sven Eckelmann <sven@narfation.org>
Link: https://lore.kernel.org/r/20211029092539.2851b4799386.If9736d4575ee79420cbec1bd930181e1d53c7317@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

2 files changed, 20 insertions, 20 deletions

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 81232b73df8f..a27b3b5fa210 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -936,33 +936,37 @@ nl80211_packet_pattern_policy[MAX_NL80211_PKTPAT + 1] = {
 	[NL80211_PKTPAT_OFFSET] = { .type = NLA_U32 },
 };
 
-int nl80211_prepare_wdev_dump(struct netlink_callback *cb,
-			      struct cfg80211_registered_device **rdev,
-			      struct wireless_dev **wdev)
+static int nl80211_prepare_wdev_dump(struct netlink_callback *cb,
+				     struct cfg80211_registered_device **rdev,
+				     struct wireless_dev **wdev,
+				     struct nlattr **attrbuf)
 {
 	int err;
 
 	if (!cb->args[0]) {
-		struct nlattr **attrbuf;
+		struct nlattr **attrbuf_free = NULL;
 
-		attrbuf = kcalloc(NUM_NL80211_ATTR, sizeof(*attrbuf),
-				  GFP_KERNEL);
-		if (!attrbuf)
-			return -ENOMEM;
+		if (!attrbuf) {
+			attrbuf = kcalloc(NUM_NL80211_ATTR, sizeof(*attrbuf),
+					  GFP_KERNEL);
+			if (!attrbuf)
+				return -ENOMEM;
+			attrbuf_free = attrbuf;
+		}
 
 		err = nlmsg_parse_deprecated(cb->nlh,
 					     GENL_HDRLEN + nl80211_fam.hdrsize,
 					     attrbuf, nl80211_fam.maxattr,
 					     nl80211_policy, NULL);
 		if (err) {
-			kfree(attrbuf);
+			kfree(attrbuf_free);
 			return err;
 		}
 
 		rtnl_lock();
 		*wdev = __cfg80211_wdev_from_attrs(NULL, sock_net(cb->skb->sk),
 						   attrbuf);
-		kfree(attrbuf);
+		kfree(attrbuf_free);
 		if (IS_ERR(*wdev)) {
 			rtnl_unlock();
 			return PTR_ERR(*wdev);
@@ -6197,7 +6201,7 @@ static int nl80211_dump_station(struct sk_buff *skb,
 	int sta_idx = cb->args[2];
 	int err;
 
-	err = nl80211_prepare_wdev_dump(cb, &rdev, &wdev);
+	err = nl80211_prepare_wdev_dump(cb, &rdev, &wdev, NULL);
 	if (err)
 		return err;
 	/* nl80211_prepare_wdev_dump acquired it in the successful case */
@@ -7092,7 +7096,7 @@ static int nl80211_dump_mpath(struct sk_buff *skb,
 	int path_idx = cb->args[2];
 	int err;
 
-	err = nl80211_prepare_wdev_dump(cb, &rdev, &wdev);
+	err = nl80211_prepare_wdev_dump(cb, &rdev, &wdev, NULL);
 	if (err)
 		return err;
 	/* nl80211_prepare_wdev_dump acquired it in the successful case */
@@ -7292,7 +7296,7 @@ static int nl80211_dump_mpp(struct sk_buff *skb,
 	int path_idx = cb->args[2];
 	int err;
 
-	err = nl80211_prepare_wdev_dump(cb, &rdev, &wdev);
+	err = nl80211_prepare_wdev_dump(cb, &rdev, &wdev, NULL);
 	if (err)
 		return err;
 	/* nl80211_prepare_wdev_dump acquired it in the successful case */
@@ -9718,7 +9722,7 @@ static int nl80211_dump_scan(struct sk_buff *skb, struct netlink_callback *cb)
 	int start = cb->args[2], idx = 0;
 	int err;
 
-	err = nl80211_prepare_wdev_dump(cb, &rdev, &wdev);
+	err = nl80211_prepare_wdev_dump(cb, &rdev, &wdev, NULL);
 	if (err)
 		return err;
 	/* nl80211_prepare_wdev_dump acquired it in the successful case */
@@ -9851,7 +9855,7 @@ static int nl80211_dump_survey(struct sk_buff *skb, struct netlink_callback *cb)
 	if (!attrbuf)
 		return -ENOMEM;
 
-	res = nl80211_prepare_wdev_dump(cb, &rdev, &wdev);
+	res = nl80211_prepare_wdev_dump(cb, &rdev, &wdev, attrbuf);
 	if (res) {
 		kfree(attrbuf);
 		return res;
diff --git a/net/wireless/nl80211.h b/net/wireless/nl80211.h
index a3f387770f1b..d642e3be4ee7 100644
--- a/net/wireless/nl80211.h
+++ b/net/wireless/nl80211.h
@@ -1,7 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /*
  * Portions of this file
- * Copyright (C) 2018, 2020 Intel Corporation
+ * Copyright (C) 2018, 2020-2021 Intel Corporation
  */
 #ifndef __NET_WIRELESS_NL80211_H
 #define __NET_WIRELESS_NL80211_H
@@ -22,10 +22,6 @@ static inline u64 wdev_id(struct wireless_dev *wdev)
 	       ((u64)wiphy_to_rdev(wdev->wiphy)->wiphy_idx << 32);
 }
 
-int nl80211_prepare_wdev_dump(struct netlink_callback *cb,
-			      struct cfg80211_registered_device **rdev,
-			      struct wireless_dev **wdev);
-
 int nl80211_parse_chandef(struct cfg80211_registered_device *rdev,
 			  struct genl_info *info,
 			  struct cfg80211_chan_def *chandef);