libertas: fix buffer overrun

If somebody sends an invalid beacon/probe response, that can trash the
whole BSS descriptor. The descriptor is, luckily, large enough so that
it cannot scribble past the end of it; it's well above 400 bytes long.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Cc: stable@kernel.org [2.6.24-2.6.27, bug present in some form since driver was added (2.6.22)]
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/libertas/scan.c b/drivers/net/wireless/libertas/scan.c
index 8f66903..22c4c61 100644 (file)
--- a/drivers/net/wireless/libertas/scan.c
+++ b/drivers/net/wireless/libertas/scan.c
@@ -598,8 +598,8 @@ static int lbs_process_bss(struct bss_descriptor *bss,
 
                switch (elem->id) {
                case MFIE_TYPE_SSID:
-                       bss->ssid_len = elem->len;
-                       memcpy(bss->ssid, elem->data, elem->len);
+                       bss->ssid_len = min_t(int, 32, elem->len);
+                       memcpy(bss->ssid, elem->data, bss->ssid_len);
                        lbs_deb_scan("got SSID IE: '%s', len %u\n",
                                     escape_essid(bss->ssid, bss->ssid_len),
                                     bss->ssid_len);