net: caif: fix memory leak in ldisc_open

[ Upstream commit 58af3d3d54e87bfc1f936e16c04ade3369d34011 ]

Syzbot reported memory leak in tty_init_dev().
The problem was in unputted tty in ldisc_open()

static int ldisc_open(struct tty_struct *tty)
{
...
	ser->tty = tty_kref_get(tty);
...
	result = register_netdevice(dev);
	if (result) {
		rtnl_unlock();
		free_netdev(dev);
		return -ENODEV;
	}
...
}

Ser pointer is netdev private_data, so after free_netdev()
this pointer goes away with unputted tty reference. So, fix
it by adding tty_kref_put() before freeing netdev.

Reported-and-tested-by: syzbot+f303e045423e617d2cad@syzkaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/caif/caif_serial.c b/drivers/net/caif/caif_serial.c
index ce76ed50a1a250b0b319b11ac2e11ce4d41d482b..1516d621e040284098f489ac4051db647aa46dd3 100644 (file)
--- a/drivers/net/caif/caif_serial.c
+++ b/drivers/net/caif/caif_serial.c
@@ -360,6 +360,7 @@ static int ldisc_open(struct tty_struct *tty)
        rtnl_lock();
        result = register_netdevice(dev);
        if (result) {
+               tty_kref_put(tty);
                rtnl_unlock();
                free_netdev(dev);
                return -ENODEV;