There is a possible issue with the use, or lack thereof of sk_refcnt and sk_wmem_alloc in the wifi ack status functionality.
Specifically if a socket were to request acknowledgements, and the socket were to have sk_refcnt drop to 0 resulting in it waiting on sk_wmem_alloc to reach 0 it would be possible to have sock_queue_err_skb orphan the last buffer, resulting in __sk_free being called on the socket. After this the buffer is enqueued on sk_error_queue, however the queue has already been flushed resulting in at least a memory leak, if not a data corruption. Signed-off-by: Alexander Duyck <[email protected]> --- net/core/skbuff.c | 5 +++++ net/mac80211/tx.c | 15 ++++----------- 2 files changed, 9 insertions(+), 11 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index c9da77a..c8259ac 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -3628,9 +3628,14 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool acked) serr->ee.ee_errno = ENOMSG; serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS; + /* take a reference to prevent skb_orphan() from freeing the socket */ + sock_hold(sk); + err = sock_queue_err_skb(sk, skb); if (err) kfree_skb(skb); + + sock_put(sk); } EXPORT_SYMBOL_GPL(skb_complete_wifi_ack); diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c index 925c39f..cf71414 100644 --- a/net/mac80211/tx.c +++ b/net/mac80211/tx.c @@ -2072,30 +2072,23 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb, if (unlikely(!multicast && skb->sk && skb_shinfo(skb)->tx_flags & SKBTX_WIFI_STATUS)) { - struct sk_buff *orig_skb = skb; + struct sk_buff *ack_skb = skb_clone_sk(skb); - skb = skb_clone(skb, GFP_ATOMIC); - if (skb) { + if (ack_skb) { unsigned long flags; int id; spin_lock_irqsave(&local->ack_status_lock, flags); - id = idr_alloc(&local->ack_status_frames, orig_skb, + id = idr_alloc(&local->ack_status_frames, ack_skb, 1, 0x10000, GFP_ATOMIC); spin_unlock_irqrestore(&local->ack_status_lock, flags); if (id >= 0) { info_id = id; info_flags |= IEEE80211_TX_CTL_REQ_TX_STATUS; - } else if (skb_shared(skb)) { - kfree_skb(orig_skb); } else { - kfree_skb(skb); - skb = orig_skb; + kfree_skb(ack_skb); } - } else { - /* couldn't clone -- lose tx status ... */ - skb = orig_skb; } } -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
