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Fix a race between ngs_rcvmsg() and soclose() which closes the control

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socket while it is still in use.
priv->ctlsock is checked at the top of the function but without any
lock held, which means the control socket state may certainly change.
Add a similar protection to ngs_shutdown() even if a race is unlikely
to be experienced there.

Sponsored by:	Sandvine Incorporated
Obtained from:	Nima Misaghian @ Sandvine Incorporated
		<nmisaghian at sandvine dot com>
MFC after:	10 days
This commit is contained in:
Attilio Rao 2010-05-19 15:06:09 +00:00
parent 0b9626482b
commit b1b11ad27e
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=208300
1 changed files with 26 additions and 6 deletions
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32
sys/netgraph/ng_socket.c
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@ -855,7 +855,7 @@ static int
ngs_rcvmsg(node_p node, item_p item, hook_p lasthook)
{
struct ngsock *const priv = NG_NODE_PRIVATE(node);
struct ngpcb *const pcbp = priv->ctlsock;
struct ngpcb *pcbp;
struct socket *so;
struct sockaddr_ng addr;
struct ng_mesg *msg;
@ -867,16 +867,28 @@ ngs_rcvmsg(node_p node, item_p item, hook_p lasthook)
NGI_GET_MSG(item, msg);
NG_FREE_ITEM(item);
/*
* Grab priv->mtx here to prevent destroying of control socket
* after checking that priv->ctlsock is not NULL.
*/
mtx_lock(&priv->mtx);
pcbp = priv->ctlsock;
/*
* Only allow mesgs to be passed if we have the control socket.
* Data sockets can only support the generic messages.
*/
if (pcbp == NULL) {
mtx_unlock(&priv->mtx);
TRAP_ERROR;
NG_FREE_MSG(msg);
return (EINVAL);
}
so = pcbp->ng_socket;
SOCKBUF_LOCK(&so->so_rcv);
/* As long as the race is handled, priv->mtx may be unlocked now. */
mtx_unlock(&priv->mtx);
#ifdef TRACE_MESSAGES
printf("[%x]:---------->[socket]: c=<%d>cmd=%x(%s) f=%x #%d\n",
@ -899,6 +911,8 @@ ngs_rcvmsg(node_p node, item_p item, hook_p lasthook)
default:
error = EINVAL; /* unknown command */
}
SOCKBUF_UNLOCK(&so->so_rcv);
/* Free the message and return. */
NG_FREE_MSG(msg);
return (error);
@ -911,6 +925,7 @@ ngs_rcvmsg(node_p node, item_p item, hook_p lasthook)
addrlen = snprintf((char *)&addr.sg_data, sizeof(addr.sg_data),
"[%x]:", retaddr);
if (addrlen < 0 || addrlen > sizeof(addr.sg_data)) {
SOCKBUF_UNLOCK(&so->so_rcv);
printf("%s: snprintf([%x]) failed - %d\n", __func__, retaddr,
addrlen);
NG_FREE_MSG(msg);
@ -928,17 +943,20 @@ ngs_rcvmsg(node_p node, item_p item, hook_p lasthook)
NG_FREE_MSG(msg);
if (m == NULL) {
SOCKBUF_UNLOCK(&so->so_rcv);
TRAP_ERROR;
return (ENOBUFS);
}
/* Send it up to the socket. */
if (sbappendaddr(&so->so_rcv, (struct sockaddr *)&addr, m, NULL) == 0) {
if (sbappendaddr_locked(&so->so_rcv, (struct sockaddr *)&addr, m,
NULL) == 0) {
SOCKBUF_UNLOCK(&so->so_rcv);
TRAP_ERROR;
m_freem(m);
return (ENOBUFS);
}
sorwakeup(so);
sorwakeup_locked(so);
return (error);
}
@ -1020,8 +1038,11 @@ static int
ngs_shutdown(node_p node)
{
struct ngsock *const priv = NG_NODE_PRIVATE(node);
struct ngpcb *const dpcbp = priv->datasock;
struct ngpcb *const pcbp = priv->ctlsock;
struct ngpcb *dpcbp, *pcbp;
mtx_lock(&priv->mtx);
dpcbp = priv->datasock;
pcbp = priv->ctlsock;
if (dpcbp != NULL)
soisdisconnected(dpcbp->ng_socket);
@ -1029,7 +1050,6 @@ ngs_shutdown(node_p node)
if (pcbp != NULL)
soisdisconnected(pcbp->ng_socket);
mtx_lock(&priv->mtx);
priv->node = NULL;
NG_NODE_SET_PRIVATE(node, NULL);
ng_socket_free_priv(priv);