l2tp: ensure sessions are freed after their PPPOL2TP socket
commit cdd10c9627496ad25c87ce6394e29752253c69d3 upstream. If l2tp_tunnel_delete() or l2tp_tunnel_closeall() deletes a session right after pppol2tp_release() orphaned its socket, then the 'sock' variable of the pppol2tp_session_close() callback is NULL. Yet the session is still used by pppol2tp_release(). Therefore we need to take an extra reference in any case, to prevent l2tp_tunnel_delete() or l2tp_tunnel_closeall() from freeing the session. Since the pppol2tp_session_close() callback is only set if the session is associated to a PPPOL2TP socket and that both l2tp_tunnel_delete() and l2tp_tunnel_closeall() hold the PPPOL2TP socket before calling pppol2tp_session_close(), we're sure that pppol2tp_session_close() and pppol2tp_session_destruct() are paired and called in the right order. So the reference taken by the former will be released by the later. Signed-off-by: Guillaume Nault <g.nault@alphalink.fr> Signed-off-by: David S. Miller <davem@davemloft.net> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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@ -455,11 +455,11 @@ static void pppol2tp_session_close(struct l2tp_session *session)
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BUG_ON(session->magic != L2TP_SESSION_MAGIC);
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if (sock) {
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if (sock)
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inet_shutdown(sock, 2);
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/* Don't let the session go away before our socket does */
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l2tp_session_inc_refcount(session);
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}
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/* Don't let the session go away before our socket does */
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l2tp_session_inc_refcount(session);
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return;
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}
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