Code: static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
{
	struct cfg80211_registered_device *rdev = info->user_ptr[0];
	struct net_device *dev = info->user_ptr[1];
	struct cfg80211_scan_request *request;
	struct nlattr *attr;
	struct wiphy *wiphy;
	int err, tmp, n_ssids = 0, n_channels, i;
	enum ieee80211_band band;
	size_t ie_len;

	if (!is_valid_ie_attr(info->attrs[NL80211_ATTR_IE]))
		return -EINVAL;

	wiphy = &rdev->wiphy;

	if (!rdev->ops->scan)
		return -EOPNOTSUPP;

	if (rdev->scan_req)
		return -EBUSY;

	if (info->attrs[NL80211_ATTR_SCAN_FREQUENCIES]) {
		n_channels = validate_scan_freqs(
				info->attrs[NL80211_ATTR_SCAN_FREQUENCIES]);
		if (!n_channels)
			return -EINVAL;
	} else {
		n_channels = 0;

		for (band = 0; band < IEEE80211_NUM_BANDS; band++)
			if (wiphy->bands[band])
				n_channels += wiphy->bands[band]->n_channels;
	}

	if (info->attrs[NL80211_ATTR_SCAN_SSIDS])
		nla_for_each_nested(attr, info->attrs[NL80211_ATTR_SCAN_SSIDS], tmp)
			n_ssids++;

	if (n_ssids > wiphy->max_scan_ssids)
		return -EINVAL;

	if (info->attrs[NL80211_ATTR_IE])
		ie_len = nla_len(info->attrs[NL80211_ATTR_IE]);
	else
		ie_len = 0;

	if (ie_len > wiphy->max_scan_ie_len)
		return -EINVAL;

	request = kzalloc(sizeof(*request)
			+ sizeof(*request->ssids) * n_ssids
			+ sizeof(*request->channels) * n_channels
			+ ie_len, GFP_KERNEL);
	if (!request)
		return -ENOMEM;

	if (n_ssids)
		request->ssids = (void *)&request->channels[n_channels];
	request->n_ssids = n_ssids;
	if (ie_len) {
		if (request->ssids)
			request->ie = (void *)(request->ssids + n_ssids);
		else
			request->ie = (void *)(request->channels + n_channels);
	}

	i = 0;
	if (info->attrs[NL80211_ATTR_SCAN_FREQUENCIES]) {
		/* user specified, bail out if channel not found */
		nla_for_each_nested(attr, info->attrs[NL80211_ATTR_SCAN_FREQUENCIES], tmp) {
			struct ieee80211_channel *chan;

			chan = ieee80211_get_channel(wiphy, nla_get_u32(attr));

			if (!chan) {
				err = -EINVAL;
				goto out_free;
			}

			/* ignore disabled channels */
			if (chan->flags & IEEE80211_CHAN_DISABLED)
				continue;

			request->channels[i] = chan;
			i++;
		}
	} else {
		/* all channels */
		for (band = 0; band < IEEE80211_NUM_BANDS; band++) {
			int j;
			if (!wiphy->bands[band])
				continue;
			for (j = 0; j < wiphy->bands[band]->n_channels; j++) {
				struct ieee80211_channel *chan;

				chan = &wiphy->bands[band]->channels[j];

				if (chan->flags & IEEE80211_CHAN_DISABLED)
					continue;

				request->channels[i] = chan;
				i++;
			}
		}
	}

	if (!i) {
		err = -EINVAL;
		goto out_free;
	}

	request->n_channels = i;

 	i = 0;
 	if (info->attrs[NL80211_ATTR_SCAN_SSIDS]) {
 		nla_for_each_nested(attr, info->attrs[NL80211_ATTR_SCAN_SSIDS], tmp) {
 			if (request->ssids[i].ssid_len > IEEE80211_MAX_SSID_LEN) {
 				err = -EINVAL;
 				goto out_free;
 			}
 			memcpy(request->ssids[i].ssid, nla_data(attr), nla_len(attr));
			request->ssids[i].ssid_len = nla_len(attr);
 			i++;
 		}
 	}

	if (info->attrs[NL80211_ATTR_IE]) {
		request->ie_len = nla_len(info->attrs[NL80211_ATTR_IE]);
		memcpy((void *)request->ie,
		       nla_data(info->attrs[NL80211_ATTR_IE]),
		       request->ie_len);
	}

	request->dev = dev;
	request->wiphy = &rdev->wiphy;

	rdev->scan_req = request;
	err = rdev->ops->scan(&rdev->wiphy, dev, request);

	if (!err) {
		nl80211_send_scan_start(rdev, dev);
		dev_hold(dev);
	} else {
 out_free:
		rdev->scan_req = NULL;
		kfree(request);
	}

	return err;
}

Vulnerability Type: Overflow +Priv 
CWE ID: CWE-119
Summary: Multiple buffer overflows in net/wireless/nl80211.c in the Linux kernel before 2.6.39.2 allow local users to gain privileges by leveraging the CAP_NET_ADMIN capability during scan operations with a long SSID value.
Commit Message: nl80211: fix check for valid SSID size in scan operations

In both trigger_scan and sched_scan operations, we were checking for
the SSID length before assigning the value correctly.  Since the
memory was just kzalloc'ed, the check was always failing and SSID with
over 32 characters were allowed to go through.

This was causing a buffer overflow when copying the actual SSID to the
proper place.

This bug has been there since 2.6.29-rc4.

Cc: stable@kernel.org
Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>