Commit a220858d authored by Johannes Berg's avatar Johannes Berg Committed by John W. Linville

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: default avatarJohannes Berg <>
Signed-off-by: default avatarJohn W. Linville <>
parent b1720231
......@@ -1089,7 +1089,7 @@ static int __ieee80211_tx(struct ieee80211_local *local,
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 @@ static int __ieee80211_tx(struct ieee80211_local *local,
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)) {
if (ret != NETDEV_TX_OK)
return IEEE80211_TX_AGAIN;
*skbp = skb = next;
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