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l2tp: Restore socket refcount when sendmsg succeeds

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[ Upstream commit 8b82547e33 ]

The sendmsg() syscall handler for PPPoL2TP doesn't decrease the socket
reference counter after successful transmissions. Any successful
sendmsg() call from userspace will then increase the reference counter
forever, thus preventing the kernel's session and tunnel data from
being freed later on.

The problem only happens when writing directly on L2TP sockets.
PPP sockets attached to L2TP are unaffected as the PPP subsystem
uses pppol2tp_xmit() which symmetrically increase/decrease reference
counters.

This patch adds the missing call to sock_put() before returning from
pppol2tp_sendmsg().

Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Guillaume Nault 2013-03-01 05:02:02 +00:00 committed by Greg Kroah-Hartman
parent 0530082c35
commit 136d76de5b
1 changed files with 1 additions and 0 deletions
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1
net/l2tp/l2tp_ppp.c
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@ -360,6 +360,7 @@ static int pppol2tp_sendmsg(struct kiocb *iocb, struct socket *sock, struct msgh
l2tp_xmit_skb(session, skb, session->hdr_len);
sock_put(ps->tunnel_sock);
sock_put(sk);
return error;