From: Fedor Pchelkin pchelkin@ispras.ru

It turns out access to j1939_can_rx_register() needs to be serialized, otherwise j1939_priv can be corrupted when parallel threads call j1939_netdev_start() and j1939_can_rx_register() fails. This issue is thoroughly covered in other commit which serializes access to j1939_can_rx_register().

Change j1939_netdev_lock type to mutex so that we do not need to remove GFP_KERNEL from can_rx_register().

j1939_netdev_lock seems to be used in normal contexts where mutex usage is not prohibited.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol") Suggested-by: Alexey Khoroshilov khoroshilov@ispras.ru Signed-off-by: Fedor Pchelkin pchelkin@ispras.ru Tested-by: Oleksij Rempel o.rempel@pengutronix.de Acked-by: Oleksij Rempel o.rempel@pengutronix.de Link: https://lore.kernel.org/r/20230526171910.227615-2-pchelkin@ispras.ru Cc: stable@vger.kernel.org Signed-off-by: Marc Kleine-Budde mkl@pengutronix.de --- net/can/j1939/main.c | 22 +++++++++++----------- 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/net/can/j1939/main.c b/net/can/j1939/main.c index 821d4ff303b3..6ed79afe19a5 100644 --- a/net/can/j1939/main.c +++ b/net/can/j1939/main.c @@ -126,7 +126,7 @@ static void j1939_can_recv(struct sk_buff *iskb, void *data) #define J1939_CAN_ID CAN_EFF_FLAG #define J1939_CAN_MASK (CAN_EFF_FLAG | CAN_RTR_FLAG)

-static DEFINE_SPINLOCK(j1939_netdev_lock); +static DEFINE_MUTEX(j1939_netdev_lock);

static struct j1939_priv *j1939_priv_create(struct net_device *ndev) { @@ -220,7 +220,7 @@ static void __j1939_rx_release(struct kref *kref) j1939_can_rx_unregister(priv); j1939_ecu_unmap_all(priv); j1939_priv_set(priv->ndev, NULL); - spin_unlock(&j1939_netdev_lock); + mutex_unlock(&j1939_netdev_lock); }

/* get pointer to priv without increasing ref counter */ @@ -248,9 +248,9 @@ static struct j1939_priv *j1939_priv_get_by_ndev(struct net_device *ndev) { struct j1939_priv *priv;

- spin_lock(&j1939_netdev_lock); + mutex_lock(&j1939_netdev_lock); priv = j1939_priv_get_by_ndev_locked(ndev); - spin_unlock(&j1939_netdev_lock); + mutex_unlock(&j1939_netdev_lock);

return priv; } @@ -260,14 +260,14 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev) struct j1939_priv *priv, *priv_new; int ret;

- spin_lock(&j1939_netdev_lock); + mutex_lock(&j1939_netdev_lock); priv = j1939_priv_get_by_ndev_locked(ndev); if (priv) { kref_get(&priv->rx_kref); - spin_unlock(&j1939_netdev_lock); + mutex_unlock(&j1939_netdev_lock); return priv; } - spin_unlock(&j1939_netdev_lock); + mutex_unlock(&j1939_netdev_lock);

priv = j1939_priv_create(ndev); if (!priv) @@ -277,20 +277,20 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev) spin_lock_init(&priv->j1939_socks_lock); INIT_LIST_HEAD(&priv->j1939_socks);

- spin_lock(&j1939_netdev_lock); + mutex_lock(&j1939_netdev_lock); priv_new = j1939_priv_get_by_ndev_locked(ndev); if (priv_new) { /* Someone was faster than us, use their priv and roll * back our's. */ kref_get(&priv_new->rx_kref); - spin_unlock(&j1939_netdev_lock); + mutex_unlock(&j1939_netdev_lock); dev_put(ndev); kfree(priv); return priv_new; } j1939_priv_set(ndev, priv); - spin_unlock(&j1939_netdev_lock); + mutex_unlock(&j1939_netdev_lock);

ret = j1939_can_rx_register(priv); if (ret < 0) @@ -308,7 +308,7 @@ struct j1939_priv *j1939_netdev_start(struct net_device *ndev)

void j1939_netdev_stop(struct j1939_priv *priv) { - kref_put_lock(&priv->rx_kref, __j1939_rx_release, &j1939_netdev_lock); + kref_put_mutex(&priv->rx_kref, __j1939_rx_release, &j1939_netdev_lock); j1939_priv_put(priv); }