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Commit dd4f1072 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: fix socket refcounting in skb_complete_wifi_ack() 



TX skbs do not necessarily hold a reference on skb->sk->sk_refcnt
By the time TX completion happens, sk_refcnt might be already 0.

sock_hold()/sock_put() would then corrupt critical state, like
sk_wmem_alloc.

Fixes: bf7fa551 ("mac80211: Resolve sk_refcnt/sk_wmem_alloc issue in wifi ack path")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Alexander Duyck <alexander.h.duyck@intel.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: Soheil Hassas Yeganeh <soheil@google.com>
Cc: Willem de Bruijn <willemb@google.com>
Acked-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 146d8fef

net/core/skbuff.c

+8 −7
Original line number Diff line number Diff line
@@ -3893,7 +3893,7 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool acked) 
{

	struct sock *sk = skb->sk;

	struct sock_exterr_skb *serr;

	int err;

	int err = 1;



	skb->wifi_acked_valid = 1;

	skb->wifi_acked = acked;
@@ -3903,14 +3903,15 @@ 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);



	/* Take a reference to prevent skb_orphan() from freeing the socket,

	 * but only if the socket refcount is not zero.

	 */

	if (likely(atomic_inc_not_zero(&sk->sk_refcnt))) {

		err = sock_queue_err_skb(sk, skb);

		sock_put(sk);

	}

	if (err)

		kfree_skb(skb);



	sock_put(sk);

}

EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);