net: fix socket refcounting in skb_complete_tx_timestamp()

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: 62bccb8cdb69 ("net-timestamp: Make the clone operation stand-alone from phy timestamping")
Signed-off-by: Eric Dumazet <[email protected]>
Cc: Alexander Duyck <[email protected]>
Cc: Johannes Berg <[email protected]>
Cc: Soheil Hassas Yeganeh <[email protected]>
Cc: Willem de Bruijn <[email protected]>
Acked-by: Soheil Hassas Yeganeh <[email protected]>
Signed-off-by: David S. Miller <[email protected]>