[PATCH] RDMA/siw: Remove direct link to net_device

[Bernard Metzler <bmt@zurich.ibm.com>]

Maintain needed network interface information locally, but
remove a direct link to net_device which can become stale.
Accessing a stale net_device link was causing a 'KASAN:
slab-use-after-free' exception during siw_query_port()
call.

Fixes: bdcf26bf9b3a ("rdma/siw: network and RDMA core interface")
Reported-by: syzbot+4b87489410b4efd181bf@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=4b87489410b4efd181bf
Signed-off-by: Bernard Metzler <bmt@zurich.ibm.com>
---
 drivers/infiniband/sw/siw/siw.h       | 11 +++++++----
 drivers/infiniband/sw/siw/siw_cm.c    |  4 ++--
 drivers/infiniband/sw/siw/siw_main.c  | 18 ++++++++++++------
 drivers/infiniband/sw/siw/siw_verbs.c | 11 ++++++-----
 4 files changed, 27 insertions(+), 17 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw.h b/drivers/infiniband/sw/siw/siw.h
index 86d4d6a2170e..c8f75527b513 100644
--- a/drivers/infiniband/sw/siw/siw.h
+++ b/drivers/infiniband/sw/siw/siw.h
@@ -69,16 +69,19 @@ struct siw_pd {
 
 struct siw_device {
 	struct ib_device base_dev;
-	struct net_device *netdev;
 	struct siw_dev_cap attrs;
 
 	u32 vendor_part_id;
+	struct {
+		int ifindex;
+		enum ib_port_state state;
+		enum ib_mtu mtu;
+		enum ib_mtu max_mtu;
+	} ifinfo;
+
 	int numa_node;
 	char raw_gid[ETH_ALEN];
 
-	/* physical port state (only one port per device) */
-	enum ib_port_state state;
-
 	spinlock_t lock;
 
 	struct xarray qp_xa;
diff --git a/drivers/infiniband/sw/siw/siw_cm.c b/drivers/infiniband/sw/siw/siw_cm.c
index 86323918a570..451b50d92f7f 100644
--- a/drivers/infiniband/sw/siw/siw_cm.c
+++ b/drivers/infiniband/sw/siw/siw_cm.c
@@ -1780,7 +1780,7 @@ int siw_create_listen(struct iw_cm_id *id, int backlog)
 
 		/* For wildcard addr, limit binding to current device only */
 		if (ipv4_is_zeronet(laddr->sin_addr.s_addr))
-			s->sk->sk_bound_dev_if = sdev->netdev->ifindex;
+			s->sk->sk_bound_dev_if = sdev->ifinfo.ifindex;
 
 		rv = s->ops->bind(s, (struct sockaddr *)laddr,
 				  sizeof(struct sockaddr_in));
@@ -1798,7 +1798,7 @@ int siw_create_listen(struct iw_cm_id *id, int backlog)
 
 		/* For wildcard addr, limit binding to current device only */
 		if (ipv6_addr_any(&laddr->sin6_addr))
-			s->sk->sk_bound_dev_if = sdev->netdev->ifindex;
+			s->sk->sk_bound_dev_if = sdev->ifinfo.ifindex;
 
 		rv = s->ops->bind(s, (struct sockaddr *)laddr,
 				  sizeof(struct sockaddr_in6));
diff --git a/drivers/infiniband/sw/siw/siw_main.c b/drivers/infiniband/sw/siw/siw_main.c
index 17abef48abcd..4db10bdfb515 100644
--- a/drivers/infiniband/sw/siw/siw_main.c
+++ b/drivers/infiniband/sw/siw/siw_main.c
@@ -287,7 +287,6 @@ static struct siw_device *siw_device_create(struct net_device *netdev)
 		return NULL;
 
 	base_dev = &sdev->base_dev;
-	sdev->netdev = netdev;
 
 	if (netdev->addr_len) {
 		memcpy(sdev->raw_gid, netdev->dev_addr,
@@ -354,6 +353,10 @@ static struct siw_device *siw_device_create(struct net_device *netdev)
 	atomic_set(&sdev->num_mr, 0);
 	atomic_set(&sdev->num_pd, 0);
 
+	sdev->ifinfo.max_mtu = ib_mtu_int_to_enum(netdev->max_mtu);
+	sdev->ifinfo.mtu = ib_mtu_int_to_enum(READ_ONCE(netdev->mtu));
+	sdev->ifinfo.ifindex = netdev->ifindex;
+
 	sdev->numa_node = dev_to_node(&netdev->dev);
 	spin_lock_init(&sdev->lock);
 
@@ -381,12 +384,12 @@ static int siw_netdev_event(struct notifier_block *nb, unsigned long event,
 
 	switch (event) {
 	case NETDEV_UP:
-		sdev->state = IB_PORT_ACTIVE;
+		sdev->ifinfo.state = IB_PORT_ACTIVE;
 		siw_port_event(sdev, 1, IB_EVENT_PORT_ACTIVE);
 		break;
 
 	case NETDEV_DOWN:
-		sdev->state = IB_PORT_DOWN;
+		sdev->ifinfo.state = IB_PORT_DOWN;
 		siw_port_event(sdev, 1, IB_EVENT_PORT_ERR);
 		break;
 
@@ -406,10 +409,13 @@ static int siw_netdev_event(struct notifier_block *nb, unsigned long event,
 	case NETDEV_CHANGEADDR:
 		siw_port_event(sdev, 1, IB_EVENT_LID_CHANGE);
 		break;
+
+	case NETDEV_CHANGEMTU:
+		sdev->ifinfo.mtu = ib_mtu_int_to_enum(READ_ONCE(netdev->mtu));
+		break;
 	/*
 	 * Todo: Below netdev events are currently not handled.
 	 */
-	case NETDEV_CHANGEMTU:
 	case NETDEV_CHANGE:
 		break;
 
@@ -444,9 +450,9 @@ static int siw_newlink(const char *basedev_name, struct net_device *netdev)
 		dev_dbg(&netdev->dev, "siw: new device\n");
 
 		if (netif_running(netdev) && netif_carrier_ok(netdev))
-			sdev->state = IB_PORT_ACTIVE;
+			sdev->ifinfo.state = IB_PORT_ACTIVE;
 		else
-			sdev->state = IB_PORT_DOWN;
+			sdev->ifinfo.state = IB_PORT_DOWN;
 
 		ib_mark_name_assigned_by_user(&sdev->base_dev);
 		rv = siw_device_register(sdev, basedev_name);
diff --git a/drivers/infiniband/sw/siw/siw_verbs.c b/drivers/infiniband/sw/siw/siw_verbs.c
index 986666c19378..3ab9c5170637 100644
--- a/drivers/infiniband/sw/siw/siw_verbs.c
+++ b/drivers/infiniband/sw/siw/siw_verbs.c
@@ -178,14 +178,15 @@ int siw_query_port(struct ib_device *base_dev, u32 port,
 
 	rv = ib_get_eth_speed(base_dev, port, &attr->active_speed,
 			 &attr->active_width);
+
 	attr->gid_tbl_len = 1;
 	attr->max_msg_sz = -1;
-	attr->max_mtu = ib_mtu_int_to_enum(sdev->netdev->mtu);
-	attr->active_mtu = ib_mtu_int_to_enum(sdev->netdev->mtu);
-	attr->phys_state = sdev->state == IB_PORT_ACTIVE ?
+	attr->max_mtu = sdev->ifinfo.max_mtu;
+	attr->active_mtu = sdev->ifinfo.mtu;
+	attr->phys_state = sdev->ifinfo.state == IB_PORT_ACTIVE ?
 		IB_PORT_PHYS_STATE_LINK_UP : IB_PORT_PHYS_STATE_DISABLED;
 	attr->port_cap_flags = IB_PORT_CM_SUP | IB_PORT_DEVICE_MGMT_SUP;
-	attr->state = sdev->state;
+	attr->state = sdev->ifinfo.state;
 	/*
 	 * All zero
 	 *
@@ -519,7 +520,7 @@ int siw_query_qp(struct ib_qp *base_qp, struct ib_qp_attr *qp_attr,
 	qp_attr->cap.max_send_sge = qp->attrs.sq_max_sges;
 	qp_attr->cap.max_recv_wr = qp->attrs.rq_size;
 	qp_attr->cap.max_recv_sge = qp->attrs.rq_max_sges;
-	qp_attr->path_mtu = ib_mtu_int_to_enum(sdev->netdev->mtu);
+	qp_attr->path_mtu = sdev->ifinfo.mtu;
 	qp_attr->max_rd_atomic = qp->attrs.irq_size;
 	qp_attr->max_dest_rd_atomic = qp->attrs.orq_size;
 
-- 
2.38.1