b43legacy: drop packets we are not able to encrypt

We must drop any packets we are not able to encrypt.
We must not send them unencrypted or with an all-zero-key (which
basically is the same as unencrypted, from a security point of view).

This might only trigger shortly after resume before mac80211 reassociated
and reconfigured the keys.

It is safe to drop these packets, as the association they belong to
is not guaranteed anymore anyway.
This is a security fix in the sense that it prevents information leakage.

This patch by Michael Buesch has been ported to b43legacy.

Cc: Michael Buesch <mb@bu3sch.de>
Signed-off-by: Stefano Brivio <stefano.brivio@polimi.it>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 15 insertions, 3 deletions

diff --git a/drivers/net/wireless/b43legacy/pio.c b/drivers/net/wireless/b43legacy/pio.c
index 1f48ec7fbe9a..bcdd54eb2edb 100644
--- a/drivers/net/wireless/b43legacy/pio.c
+++ b/drivers/net/wireless/b43legacy/pio.c
@@ -181,7 +181,7 @@ union txhdr_union {
         struct b43legacy_txhdr_fw3 txhdr_fw3;
 };
 
-static void pio_tx_write_fragment(struct b43legacy_pioqueue *queue,
+static int pio_tx_write_fragment(struct b43legacy_pioqueue *queue,
                                   struct sk_buff *skb,
                                   struct b43legacy_pio_txpacket *packet,
                                   size_t txhdr_size)
@@ -189,14 +189,17 @@ static void pio_tx_write_fragment(struct b43legacy_pioqueue *queue,
         union txhdr_union txhdr_data;
         u8 *txhdr = NULL;
         unsigned int octets;
+        int err;
 
         txhdr = (u8 *)(&txhdr_data.txhdr_fw3);
 
         B43legacy_WARN_ON(skb_shinfo(skb)->nr_frags != 0);
-        b43legacy_generate_txhdr(queue->dev,
+        err = b43legacy_generate_txhdr(queue->dev,
                                  txhdr, skb->data, skb->len,
                                  &packet->txstat.control,
                                  generate_cookie(queue, packet));
+        if (err)
+                return err;
 
         tx_start(queue);
         octets = skb->len + txhdr_size;
@@ -204,6 +207,8 @@ static void pio_tx_write_fragment(struct b43legacy_pioqueue *queue,
                 octets--;
         tx_data(queue, txhdr, (u8 *)skb->data, octets);
         tx_complete(queue, skb);
+
+        return 0;
 }
 
 static void free_txpacket(struct b43legacy_pio_txpacket *packet,
@@ -226,6 +231,7 @@ static int pio_tx_packet(struct b43legacy_pio_txpacket *packet)
         struct b43legacy_pioqueue *queue = packet->queue;
         struct sk_buff *skb = packet->skb;
         u16 octets;
+        int err;
 
         octets = (u16)skb->len + sizeof(struct b43legacy_txhdr_fw3);
         if (queue->tx_devq_size < octets) {
@@ -247,8 +253,14 @@ static int pio_tx_packet(struct b43legacy_pio_txpacket *packet)
         if (queue->tx_devq_used + octets > queue->tx_devq_size)
                 return -EBUSY;
         /* Now poke the device. */
-        pio_tx_write_fragment(queue, skb, packet,
+        err = pio_tx_write_fragment(queue, skb, packet,
                               sizeof(struct b43legacy_txhdr_fw3));
+        if (unlikely(err == -ENOKEY)) {
+                /* Drop this packet, as we don't have the encryption key
+                 * anymore and must not transmit it unencrypted. */
+                free_txpacket(packet, 1);
+                return 0;
+        }
 
         /* Account for the packet size.
          * (We must not overflow the device TX queue)