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mac80211: Resolve sk_refcnt/sk_wmem_alloc issue in wifi ack path 

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 <alexander.h.duyck@intel.com>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Duyck 2014-09-10 18:05:42 -04:00 committed by David S. Miller
parent cab41c47d9
commit bf7fa551e0
2 changed files with 9 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
net/core/skbuff.c
View File

@ -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);

15
net/mac80211/tx.c
View File

@ -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;
}
}