| From cdd10c9627496ad25c87ce6394e29752253c69d3 Mon Sep 17 00:00:00 2001 |
| From: Guillaume Nault <g.nault@alphalink.fr> |
| Date: Fri, 22 Sep 2017 15:39:23 +0200 |
| Subject: l2tp: ensure sessions are freed after their PPPOL2TP socket |
| |
| From: Guillaume Nault <g.nault@alphalink.fr> |
| |
| 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> |
| Signed-off-by: Will Deacon <will@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| net/l2tp/l2tp_ppp.c | 8 ++++---- |
| 1 file changed, 4 insertions(+), 4 deletions(-) |
| |
| --- a/net/l2tp/l2tp_ppp.c |
| +++ b/net/l2tp/l2tp_ppp.c |
| @@ -437,11 +437,11 @@ static void pppol2tp_session_close(struc |
| |
| BUG_ON(session->magic != L2TP_SESSION_MAGIC); |
| |
| - if (sock) { |
| + if (sock) |
| inet_shutdown(sock, SEND_SHUTDOWN); |
| - /* Don't let the session go away before our socket does */ |
| - l2tp_session_inc_refcount(session); |
| - } |
| + |
| + /* Don't let the session go away before our socket does */ |
| + l2tp_session_inc_refcount(session); |
| } |
| |
| /* Really kill the session socket. (Called from sock_put() if |
