[PATCH net] can: j1939: fix UAF for rx_kref of j1939_priv

Subsystems: can network layer, can-j1939 network layer, the rest

STALE1783d LANDED

Landed in mainline as d9d52a3ebd28 on 2021-10-17.

3 messages, 3 authors, 2021-10-17 · open the first message on its own page

[PATCH net] can: j1939: fix UAF for rx_kref of j1939_priv

From: Ziyang Xuan <hidden>
Date: 2021-09-26 10:49:08

It will trigger UAF for rx_kref of j1939_priv as following.

        cpu0                                    cpu1
j1939_sk_bind(socket0, ndev0, ...)
j1939_netdev_start
                                        j1939_sk_bind(socket1, ndev0, ...)
                                        j1939_netdev_start
j1939_priv_set
                                        j1939_priv_get_by_ndev_locked
j1939_jsk_add
.....
j1939_netdev_stop
kref_put_lock(&priv->rx_kref, ...)
                                        kref_get(&priv->rx_kref, ...)
                                        REFCOUNT_WARN("addition on 0;...")

====================================================
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 20874 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0
RIP: 0010:refcount_warn_saturate+0x169/0x1e0
Call Trace:
 j1939_netdev_start+0x68b/0x920
 j1939_sk_bind+0x426/0xeb0
 ? security_socket_bind+0x83/0xb0

The rx_kref's kref_get() and kref_put() should use j1939_netdev_lock to
protect.

Fixes: 9d71dd0c70099 ("can: add support of SAE J1939 protocol")
Reported-by: syzbot+85d9878b19c94f9019ad@syzkaller.appspotmail.com
Signed-off-by: Ziyang Xuan <redacted>
---
 net/can/j1939/main.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c
index 08c8606cfd9c..9bc55ecb37f9 100644
--- a/net/can/j1939/main.c
+++ b/net/can/j1939/main.c

@@ -249,11 +249,14 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
 	struct j1939_priv *priv, *priv_new;
 	int ret;
 
-	priv = j1939_priv_get_by_ndev(ndev);
+	spin_lock(&j1939_netdev_lock);
+	priv = j1939_priv_get_by_ndev_locked(ndev);
 	if (priv) {
 		kref_get(&priv->rx_kref);
+		spin_unlock(&j1939_netdev_lock);
 		return priv;
 	}
+	spin_unlock(&j1939_netdev_lock);
 
 	priv = j1939_priv_create(ndev);
 	if (!priv)

@@ -269,10 +272,10 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
 		/* Someone was faster than us, use their priv and roll
 		 * back our's.
 		 */
+		kref_get(&priv_new->rx_kref);
 		spin_unlock(&j1939_netdev_lock);
 		dev_put(ndev);
 		kfree(priv);
-		kref_get(&priv_new->rx_kref);
 		return priv_new;
 	}
 	j1939_priv_set(ndev, priv);

-- 
2.25.1

Re: [PATCH net] can: j1939: fix UAF for rx_kref of j1939_priv

From: Oleksij Rempel <o.rempel@pengutronix.de>
Date: 2021-10-08 11:47:48

Hi,

On Sun, Sep 26, 2021 at 06:47:57PM +0800, Ziyang Xuan wrote:

It will trigger UAF for rx_kref of j1939_priv as following.

        cpu0                                    cpu1
j1939_sk_bind(socket0, ndev0, ...)
j1939_netdev_start
                                        j1939_sk_bind(socket1, ndev0, ...)
                                        j1939_netdev_start
j1939_priv_set
                                        j1939_priv_get_by_ndev_locked
j1939_jsk_add
.....
j1939_netdev_stop
kref_put_lock(&priv->rx_kref, ...)
                                        kref_get(&priv->rx_kref, ...)
                                        REFCOUNT_WARN("addition on 0;...")

====================================================
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 20874 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0
RIP: 0010:refcount_warn_saturate+0x169/0x1e0
Call Trace:
 j1939_netdev_start+0x68b/0x920
 j1939_sk_bind+0x426/0xeb0
 ? security_socket_bind+0x83/0xb0

The rx_kref's kref_get() and kref_put() should use j1939_netdev_lock to
protect.

Fixes: 9d71dd0c70099 ("can: add support of SAE J1939 protocol")
Reported-by: syzbot+85d9878b19c94f9019ad@syzkaller.appspotmail.com
Signed-off-by: Ziyang Xuan <redacted>

Thank you!

Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>

quoted hunk

---
 net/can/j1939/main.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c
index 08c8606cfd9c..9bc55ecb37f9 100644
--- a/net/can/j1939/main.c
+++ b/net/can/j1939/main.c

@@ -249,11 +249,14 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
 	struct j1939_priv *priv, *priv_new;
 	int ret;
 
-	priv = j1939_priv_get_by_ndev(ndev);
+	spin_lock(&j1939_netdev_lock);
+	priv = j1939_priv_get_by_ndev_locked(ndev);
 	if (priv) {
 		kref_get(&priv->rx_kref);
+		spin_unlock(&j1939_netdev_lock);
 		return priv;
 	}
+	spin_unlock(&j1939_netdev_lock);
 
 	priv = j1939_priv_create(ndev);
 	if (!priv)

@@ -269,10 +272,10 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev)
 		/* Someone was faster than us, use their priv and roll
 		 * back our's.
 		 */
+		kref_get(&priv_new->rx_kref);
 		spin_unlock(&j1939_netdev_lock);
 		dev_put(ndev);
 		kfree(priv);
-		kref_get(&priv_new->rx_kref);
 		return priv_new;
 	}
 	j1939_priv_set(ndev, priv);

-- 
2.25.1

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

Re: [PATCH net] can: j1939: fix UAF for rx_kref of j1939_priv

From: Marc Kleine-Budde <mkl@pengutronix.de>
Date: 2021-10-17 10:48:41

On 26.09.2021 18:47:57, Ziyang Xuan wrote:

It will trigger UAF for rx_kref of j1939_priv as following.

        cpu0                                    cpu1
j1939_sk_bind(socket0, ndev0, ...)
j1939_netdev_start
                                        j1939_sk_bind(socket1, ndev0, ...)
                                        j1939_netdev_start
j1939_priv_set
                                        j1939_priv_get_by_ndev_locked
j1939_jsk_add
.....
j1939_netdev_stop
kref_put_lock(&priv->rx_kref, ...)
                                        kref_get(&priv->rx_kref, ...)
                                        REFCOUNT_WARN("addition on 0;...")

====================================================
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 1 PID: 20874 at lib/refcount.c:25 refcount_warn_saturate+0x169/0x1e0
RIP: 0010:refcount_warn_saturate+0x169/0x1e0
Call Trace:
 j1939_netdev_start+0x68b/0x920
 j1939_sk_bind+0x426/0xeb0
 ? security_socket_bind+0x83/0xb0

The rx_kref's kref_get() and kref_put() should use j1939_netdev_lock to
protect.

Fixes: 9d71dd0c70099 ("can: add support of SAE J1939 protocol")
Reported-by: syzbot+85d9878b19c94f9019ad@syzkaller.appspotmail.com
Signed-off-by: Ziyang Xuan <redacted>

Added to linux-can/testing, added stable on Cc.

Thanks,
Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

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