From 0635b36293a7e5338a0b23a7fc2b0c8b3619de88 Mon Sep 17 00:00:00 2001
From: Johannes Berg <johannes.berg@intel.com>
Date: Fri, 1 Mar 2013 14:03:49 +0100
Subject: [PATCH] --- yaml --- r: 361064 b: refs/heads/master c:
 645e77def93f1dd0e211c7244fbe152dac8a7100 h: refs/heads/master v: v3

---
 [refs]                       |  2 +-
 trunk/net/wireless/nl80211.c | 30 +++++++++++++++++++++++++-----
 2 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/[refs] b/[refs]
index 21c251d470da..656fc778717e 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: feda30271e5455394c57e35eba66db88d1b15077
+refs/heads/master: 645e77def93f1dd0e211c7244fbe152dac8a7100
diff --git a/trunk/net/wireless/nl80211.c b/trunk/net/wireless/nl80211.c
index 7a7b621d45fd..d44ab216c0ec 100644
--- a/trunk/net/wireless/nl80211.c
+++ b/trunk/net/wireless/nl80211.c
@@ -1307,7 +1307,7 @@ static int nl80211_send_wiphy(struct sk_buff *msg, u32 portid, u32 seq, int flag
 
 static int nl80211_dump_wiphy(struct sk_buff *skb, struct netlink_callback *cb)
 {
-	int idx = 0;
+	int idx = 0, ret;
 	int start = cb->args[0];
 	struct cfg80211_registered_device *dev;
 
@@ -1317,9 +1317,29 @@ static int nl80211_dump_wiphy(struct sk_buff *skb, struct netlink_callback *cb)
 			continue;
 		if (++idx <= start)
 			continue;
-		if (nl80211_send_wiphy(skb, NETLINK_CB(cb->skb).portid,
-				       cb->nlh->nlmsg_seq, NLM_F_MULTI,
-				       dev) < 0) {
+		ret = nl80211_send_wiphy(skb, NETLINK_CB(cb->skb).portid,
+					 cb->nlh->nlmsg_seq, NLM_F_MULTI,
+					 dev);
+		if (ret < 0) {
+			/*
+			 * If sending the wiphy data didn't fit (ENOBUFS or
+			 * EMSGSIZE returned), this SKB is still empty (so
+			 * it's not too big because another wiphy dataset is
+			 * already in the skb) and we've not tried to adjust
+			 * the dump allocation yet ... then adjust the alloc
+			 * size to be bigger, and return 1 but with the empty
+			 * skb. This results in an empty message being RX'ed
+			 * in userspace, but that is ignored.
+			 *
+			 * We can then retry with the larger buffer.
+			 */
+			if ((ret == -ENOBUFS || ret == -EMSGSIZE) &&
+			    !skb->len &&
+			    cb->min_dump_alloc < 4096) {
+				cb->min_dump_alloc = 4096;
+				mutex_unlock(&cfg80211_mutex);
+				return 1;
+			}
 			idx--;
 			break;
 		}
@@ -1336,7 +1356,7 @@ static int nl80211_get_wiphy(struct sk_buff *skb, struct genl_info *info)
 	struct sk_buff *msg;
 	struct cfg80211_registered_device *dev = info->user_ptr[0];
 
-	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	msg = nlmsg_new(4096, GFP_KERNEL);
 	if (!msg)
 		return -ENOMEM;