[PATCH 4.9 61/71] net: caif: fix memory leak in ldisc_open

Sasha Levin
2021-06-28T15:22:19Z

From: Pavel Skripkin <paskripkin@gmail.com>

[ 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>
---
drivers/net/caif/caif_serial.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/net/caif/caif_serial.c b/drivers/net/caif/caif_serial.c
index 32834dad0b83..1243c2e5a86a 100644
--- a/drivers/net/caif/caif_serial.c
+++ b/drivers/net/caif/caif_serial.c
@@ -362,6 +362,7 @@ 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;
--
2.30.2