[PATCH 4.19 213/243] xfrm interface: avoid corruption on changelink

Greg Kroah-Hartman
2019-12-11T15:25:04Z

From: Nicolas Dichtel <nicolas.dichtel@6wind.com>

commit e9e7e85d75f3731079ffd77c1a66f037aef04fe7 upstream.

The new parameters must not be stored in the netdev_priv() before
validation, it may corrupt the interface. Note also that if data is NULL,
only a memset() is done.

$ ip link add xfrm1 type xfrm dev lo if_id 1
$ ip link add xfrm2 type xfrm dev lo if_id 2
$ ip link set xfrm1 type xfrm dev lo if_id 2
RTNETLINK answers: File exists
$ ip -d link list dev xfrm1
5: xfrm1@lo: <NOARP> mtu 1500 qdisc noop state DOWN mode DEFAULT group default qlen 1000
link/none 00:00:00:00:00:00 brd 00:00:00:00:00:00 promiscuity 0 minmtu 68 maxmtu 1500
xfrm if_id 0x2 addrgenmode eui64 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535

=> "if_id 0x2"

Fixes: f203b76d7809 ("xfrm: Add virtual xfrm interfaces")
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Tested-by: Julien Floret <julien.floret@6wind.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/xfrm/xfrm_interface.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

--- a/net/xfrm/xfrm_interface.c
+++ b/net/xfrm/xfrm_interface.c
@@ -674,12 +674,12 @@ static int xfrmi_changelink(struct net_d
struct nlattr *data[],
struct netlink_ext_ack *extack)
{
- struct xfrm_if *xi = netdev_priv(dev);
struct net *net = dev_net(dev);
+ struct xfrm_if_parms p;
+ struct xfrm_if *xi;

- xfrmi_netlink_parms(data, &xi->p);
-
- xi = xfrmi_locate(net, &xi->p);
+ xfrmi_netlink_parms(data, &p);
+ xi = xfrmi_locate(net, &p);
if (!xi) {
xi = netdev_priv(dev);
} else {
@@ -687,7 +687,7 @@ static int xfrmi_changelink(struct net_d
return -EEXIST;
}

- return xfrmi_update(xi, &xi->p);
+ return xfrmi_update(xi, &p);
}

static size_t xfrmi_get_size(const struct net_device *dev)