rt2x00: fix possible memory corruption in case of invalid rxdesc.size

Sometimes rxdesc descriptor provided by hardware contains invalid
(random) data. For example rxdesc.size can be bigger than actual
size of the buffer. When this happen rt2x00crypto_rx_insert_iv()
corrupt memory doing memmove outside of buffer boundaries.

Signed-off-by: Stanislaw Gruszka <stf_xl@wp.pl>
Acked-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/rt2x00/rt2x00dev.c b/drivers/net/wireless/rt2x00/rt2x00dev.c
index 939821b4af2ff5b768913cc0809b05695801285c..0955c941317fd7d7ff049b18ade0a3be8c3bd89f 100644 (file)
--- a/drivers/net/wireless/rt2x00/rt2x00dev.c
+++ b/drivers/net/wireless/rt2x00/rt2x00dev.c
@@ -582,6 +582,18 @@ void rt2x00lib_rxdone(struct queue_entry *entry)
        memset(&rxdesc, 0, sizeof(rxdesc));
        rt2x00dev->ops->lib->fill_rxdone(entry, &rxdesc);
 
+       /*
+        * Check for valid size in case we get corrupted descriptor from
+        * hardware.
+        */
+       if (unlikely(rxdesc.size == 0 ||
+                    rxdesc.size > entry->queue->data_size)) {
+               WARNING(rt2x00dev, "Wrong frame size %d max %d.\n",
+                       rxdesc.size, entry->queue->data_size);
+               dev_kfree_skb(entry->skb);
+               goto renew_skb;
+       }
+
        /*
         * The data behind the ieee80211 header must be
         * aligned on a 4 byte boundary.
@@ -642,6 +654,7 @@ void rt2x00lib_rxdone(struct queue_entry *entry)
 
        ieee80211_rx_ni(rt2x00dev->hw, entry->skb);
 
+renew_skb:
        /*
         * Replace the skb with the freshly allocated one.
         */