mac80211: add skb length sanity checking
We just found a bug in zd1211rw where it would reject
packets in the ->tx() method but leave them modified,
which would cause retransmit attempts with completely
bogus skbs, eventually leading to a panic due to not
having enough headroom in those.
This patch adds a sanity check to mac80211 to catch
such driver mistakes; in this case we warn and drop
the skb.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index b909e40..a0e00c6 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -1089,7 +1089,7 @@
{
struct sk_buff *skb = *skbp, *next;
struct ieee80211_tx_info *info;
- int ret;
+ int ret, len;
bool fragm = false;
local->mdev->trans_start = jiffies;
@@ -1125,7 +1125,12 @@
}
next = skb->next;
+ len = skb->len;
ret = local->ops->tx(local_to_hw(local), skb);
+ if (WARN_ON(ret != NETDEV_TX_OK && skb->len != len)) {
+ dev_kfree_skb(skb);
+ ret = NETDEV_TX_OK;
+ }
if (ret != NETDEV_TX_OK)
return IEEE80211_TX_AGAIN;
*skbp = skb = next;