[PATCH 3.18 16/24] nl80211: check for the required netlink attributes presence

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Vladis Dronov <vdronov@redhat.com>

commit e785fa0a164aa11001cba931367c7f94ffaff888 upstream.

nl80211_set_rekey_data() does not check if the required attributes
NL80211_REKEY_DATA_{REPLAY_CTR,KEK,KCK} are present when processing
NL80211_CMD_SET_REKEY_OFFLOAD request. This request can be issued by
users with CAP_NET_ADMIN privilege and may result in NULL dereference
and a system crash. Add a check for the required attributes presence.
This patch is based on the patch by bo Zhang.

This fixes CVE-2017-12153.

References: https://bugzilla.redhat.com/show_bug.cgi?id=1491046
Fixes: e5497d766ad ("cfg80211/nl80211: support GTK rekey offload")
Reported-by: bo Zhang <zhangbo5891001@gmail.com>
Signed-off-by: Vladis Dronov <vdronov@redhat.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/wireless/nl80211.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -9006,6 +9006,9 @@ static int nl80211_set_rekey_data(struct
 	if (err)
 		return err;
 
+	if (!tb[NL80211_REKEY_DATA_REPLAY_CTR] || !tb[NL80211_REKEY_DATA_KEK] ||
+	    !tb[NL80211_REKEY_DATA_KCK])
+		return -EINVAL;
 	if (nla_len(tb[NL80211_REKEY_DATA_REPLAY_CTR]) != NL80211_REPLAY_CTR_LEN)
 		return -ERANGE;
 	if (nla_len(tb[NL80211_REKEY_DATA_KEK]) != NL80211_KEK_LEN)