[PATCH 5.3 046/180] virt_wifi: fix use-after-free in virt_wifi_newlink()

Greg Kroah-Hartman
2019-12-16T18:34:36Z

From: Taehee Yoo <ap420073@gmail.com>

commit bc71d8b580ba81b55b6e15b1c0320632515b4bac upstream.

When virt_wifi interface is created, virt_wifi_newlink() is called and
it calls register_netdevice().
if register_netdevice() fails, it internally would call
->priv_destructor(), which is virt_wifi_net_device_destructor() and
it frees netdev. but virt_wifi_newlink() still use netdev.
So, use-after-free would occur in virt_wifi_newlink().

Test commands:
ip link add dummy0 type dummy
modprobe bonding
ip link add bonding_masters link dummy0 type virt_wifi

Splat looks like:
[ 202.220554] BUG: KASAN: use-after-free in virt_wifi_newlink+0x88b/0x9a0 [virt_wifi]
[ 202.221659] Read of size 8 at addr ffff888061629cb8 by task ip/852

[ 202.222896] CPU: 1 PID: 852 Comm: ip Not tainted 5.4.0-rc5 #3
[ 202.223765] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[ 202.225073] Call Trace:
[ 202.225532] dump_stack+0x7c/0xbb
[ 202.226869] print_address_description.constprop.5+0x1be/0x360
[ 202.229362] __kasan_report+0x12a/0x16f
[ 202.230714] kasan_report+0xe/0x20
[ 202.232595] virt_wifi_newlink+0x88b/0x9a0 [virt_wifi]
[ 202.233370] __rtnl_newlink+0xb9f/0x11b0
[ 202.244909] rtnl_newlink+0x65/0x90
[ ... ]

Cc: stable@vger.kernel.org
Fixes: c7cdba31ed8b ("mac80211-next: rtnetlink wifi simulation device")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Link: https://lore.kernel.org/r/20191121122645.9355-1-ap420073@gmail.com
[trim stack dump a bit]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/net/wireless/virt_wifi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/net/wireless/virt_wifi.c
+++ b/drivers/net/wireless/virt_wifi.c
@@ -450,7 +450,6 @@ static void virt_wifi_net_device_destruc
*/
kfree(dev->ieee80211_ptr);
dev->ieee80211_ptr = NULL;
- free_netdev(dev);
}

/* No lock interaction. */
@@ -458,7 +457,7 @@ static void virt_wifi_setup(struct net_d
{
ether_setup(dev);
dev->netdev_ops = &virt_wifi_ops;
- dev->priv_destructor = virt_wifi_net_device_destructor;
+ dev->needs_free_netdev = true;
}

/* Called in a RCU read critical section from netif_receive_skb */
@@ -544,6 +543,7 @@ static int virt_wifi_newlink(struct net
goto unregister_netdev;
}

+ dev->priv_destructor = virt_wifi_net_device_destructor;
priv->being_deleted = false;
priv->is_connected = false;
priv->is_up = false;