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Commit 9ac25fc0 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: fix socket refcounting in skb_complete_tx_timestamp() 



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 and lead to leaks or use after free.

Fixes: 62bccb8c ("net-timestamp: Make the clone operation stand-alone from phy timestamping")
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 dd4f1072

net/core/skbuff.c

+8 −7
Original line number Diff line number Diff line
@@ -3828,14 +3828,15 @@ void skb_complete_tx_timestamp(struct sk_buff *skb, 
	if (!skb_may_tx_timestamp(sk, false))

		return;



	/* 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))) {

		*skb_hwtstamps(skb) = *hwtstamps;

		__skb_complete_tx_timestamp(skb, sk, SCM_TSTAMP_SND);



		sock_put(sk);

	}

}

EXPORT_SYMBOL_GPL(skb_complete_tx_timestamp);



void __skb_tstamp_tx(struct sk_buff *orig_skb,