[PATCH] cfg80211: protect fools returning NULL in add_virtual_intf

[Rafał Miłecki <zajec5@xxxxxxxxx>]

Callback add_virtual_intf is supposed to return ERR_PTR and trying to
return NULL results in some "Unable to handle kernel paging request",
etc. As it may be complicated to debug & trace, let's catch it (WARN).

Signed-off-by: Rafał Miłecki <zajec5@xxxxxxxxx>
---
 net/wireless/nl80211.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 1a31736..eeb96c1 100644
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -2641,7 +2641,10 @@ static int nl80211_new_interface(struct sk_buff *skb, struct genl_info *info)
 	wdev = rdev_add_virtual_intf(rdev,
 				nla_data(info->attrs[NL80211_ATTR_IFNAME]),
 				type, err ? NULL : &flags, &params);
-	if (IS_ERR(wdev)) {
+	if (WARN_ON(!wdev)) {
+		nlmsg_free(msg);
+		return -EPROTO;
+	} else if (IS_ERR(wdev)) {
 		nlmsg_free(msg);
 		return PTR_ERR(wdev);
 	}
-- 
1.8.4.5

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