nl80211: fix check for valid SSID size in scan operations

commit 208c72f4fe44fe09577e7975ba0e7fa0278f3d03 upstream.

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.

Signed-off-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index 7cb0d647fc34a53414e21a752923c65d8bfe55ed..eb1674f6beaea83824994d40314cbc6aa553c9e3 100644 (file)
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -3078,12 +3078,12 @@ static int nl80211_trigger_scan(struct sk_buff *skb, struct genl_info *info)
        i = 0;
        if (info->attrs[NL80211_ATTR_SCAN_SSIDS]) {
                nla_for_each_nested(attr, info->attrs[NL80211_ATTR_SCAN_SSIDS], tmp) {
+                       request->ssids[i].ssid_len = nla_len(attr);
                        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++;
                }
        }