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l2tp: hold tunnel used while creating sessions with netlink

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Use l2tp_tunnel_get() to retrieve tunnel, so that it can't go away on
us. Otherwise l2tp_tunnel_destruct() might release the last reference
count concurrently, thus freeing the tunnel while we're using it.

Fixes: 309795f4be ("l2tp: Add netlink control API for L2TP")
Signed-off-by: Guillaume Nault <g.nault@alphalink.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Guillaume Nault 2017-08-25 16:51:46 +02:00 committed by David S. Miller
parent 4e4b21da3a
commit e702c1204e
1 changed files with 12 additions and 9 deletions
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21
net/l2tp/l2tp_netlink.c
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@ -518,8 +518,9 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
ret = -EINVAL;
goto out;
}
tunnel_id = nla_get_u32(info->attrs[L2TP_ATTR_CONN_ID]);
tunnel = l2tp_tunnel_find(net, tunnel_id);
tunnel = l2tp_tunnel_get(net, tunnel_id);
if (!tunnel) {
ret = -ENODEV;
goto out;
@ -527,24 +528,24 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
if (!info->attrs[L2TP_ATTR_SESSION_ID]) {
ret = -EINVAL;
goto out;
goto out_tunnel;
}
session_id = nla_get_u32(info->attrs[L2TP_ATTR_SESSION_ID]);
if (!info->attrs[L2TP_ATTR_PEER_SESSION_ID]) {
ret = -EINVAL;
goto out;
goto out_tunnel;
}
peer_session_id = nla_get_u32(info->attrs[L2TP_ATTR_PEER_SESSION_ID]);
if (!info->attrs[L2TP_ATTR_PW_TYPE]) {
ret = -EINVAL;
goto out;
goto out_tunnel;
}
cfg.pw_type = nla_get_u16(info->attrs[L2TP_ATTR_PW_TYPE]);
if (cfg.pw_type >= __L2TP_PWTYPE_MAX) {
ret = -EINVAL;
goto out;
goto out_tunnel;
}
if (tunnel->version > 2) {
@ -566,7 +567,7 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
u16 len = nla_len(info->attrs[L2TP_ATTR_COOKIE]);
if (len > 8) {
ret = -EINVAL;
goto out;
goto out_tunnel;
}
cfg.cookie_len = len;
memcpy(&cfg.cookie[0], nla_data(info->attrs[L2TP_ATTR_COOKIE]), len);
@ -575,7 +576,7 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
u16 len = nla_len(info->attrs[L2TP_ATTR_PEER_COOKIE]);
if (len > 8) {
ret = -EINVAL;
goto out;
goto out_tunnel;
}
cfg.peer_cookie_len = len;
memcpy(&cfg.peer_cookie[0], nla_data(info->attrs[L2TP_ATTR_PEER_COOKIE]), len);
@ -618,7 +619,7 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
if ((l2tp_nl_cmd_ops[cfg.pw_type] == NULL) ||
(l2tp_nl_cmd_ops[cfg.pw_type]->session_create == NULL)) {
ret = -EPROTONOSUPPORT;
goto out;
goto out_tunnel;
}
/* Check that pseudowire-specific params are present */
@ -628,7 +629,7 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
case L2TP_PWTYPE_ETH_VLAN:
if (!info->attrs[L2TP_ATTR_VLAN_ID]) {
ret = -EINVAL;
goto out;
goto out_tunnel;
}
break;
case L2TP_PWTYPE_ETH:
@ -656,6 +657,8 @@ static int l2tp_nl_cmd_session_create(struct sk_buff *skb, struct genl_info *inf
}
}
out_tunnel:
l2tp_tunnel_dec_refcount(tunnel);
out:
return ret;
}