net: openvswitch: free vport unless register_netdevice() succeeds

syzbot found the following crash on:

HEAD commit:    1e78030 Merge tag 'mmc-v5.3-rc1' of git://git.kernel.org/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=148d3d1a600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=30cef20daf3e9977
dashboard link: https://syzkaller.appspot.com/bug?extid=13210896153522fe1ee5
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=136aa8c4600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=109ba792600000

=====================================================================
BUG: memory leak
unreferenced object 0xffff8881207e4100 (size 128):
   comm "syz-executor032", pid 7014, jiffies 4294944027 (age 13.830s)
   hex dump (first 32 bytes):
     00 70 16 18 81 88 ff ff 80 af 8c 22 81 88 ff ff  .p........."....
     00 b6 23 17 81 88 ff ff 00 00 00 00 00 00 00 00  ..#.............
   backtrace:
     [<000000000eb78212>] kmemleak_alloc_recursive  include/linux/kmemleak.h:43 [inline]
     [<000000000eb78212>] slab_post_alloc_hook mm/slab.h:522 [inline]
     [<000000000eb78212>] slab_alloc mm/slab.c:3319 [inline]
     [<000000000eb78212>] kmem_cache_alloc_trace+0x145/0x2c0 mm/slab.c:3548
     [<00000000006ea6c6>] kmalloc include/linux/slab.h:552 [inline]
     [<00000000006ea6c6>] kzalloc include/linux/slab.h:748 [inline]
     [<00000000006ea6c6>] ovs_vport_alloc+0x37/0xf0  net/openvswitch/vport.c:130
     [<00000000f9a04a7d>] internal_dev_create+0x24/0x1d0  net/openvswitch/vport-internal_dev.c:164
     [<0000000056ee7c13>] ovs_vport_add+0x81/0x190  net/openvswitch/vport.c:199
     [<000000005434efc7>] new_vport+0x19/0x80 net/openvswitch/datapath.c:194
     [<00000000b7b253f1>] ovs_dp_cmd_new+0x22f/0x410  net/openvswitch/datapath.c:1614
     [<00000000e0988518>] genl_family_rcv_msg+0x2ab/0x5b0  net/netlink/genetlink.c:629
     [<00000000d0cc9347>] genl_rcv_msg+0x54/0x9c net/netlink/genetlink.c:654
     [<000000006694b647>] netlink_rcv_skb+0x61/0x170  net/netlink/af_netlink.c:2477
     [<0000000088381f37>] genl_rcv+0x29/0x40 net/netlink/genetlink.c:665
     [<00000000dad42a47>] netlink_unicast_kernel  net/netlink/af_netlink.c:1302 [inline]
     [<00000000dad42a47>] netlink_unicast+0x1ec/0x2d0  net/netlink/af_netlink.c:1328
     [<0000000067e6b079>] netlink_sendmsg+0x270/0x480  net/netlink/af_netlink.c:1917
     [<00000000aab08a47>] sock_sendmsg_nosec net/socket.c:637 [inline]
     [<00000000aab08a47>] sock_sendmsg+0x54/0x70 net/socket.c:657
     [<000000004cb7c11d>] ___sys_sendmsg+0x393/0x3c0 net/socket.c:2311
     [<00000000c4901c63>] __sys_sendmsg+0x80/0xf0 net/socket.c:2356
     [<00000000c10abb2d>] __do_sys_sendmsg net/socket.c:2365 [inline]
     [<00000000c10abb2d>] __se_sys_sendmsg net/socket.c:2363 [inline]
     [<00000000c10abb2d>] __x64_sys_sendmsg+0x23/0x30 net/socket.c:2363

BUG: memory leak
unreferenced object 0xffff88811723b600 (size 64):
   comm "syz-executor032", pid 7014, jiffies 4294944027 (age 13.830s)
   hex dump (first 32 bytes):
     01 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00  ................
     00 00 00 00 00 00 00 00 02 00 00 00 05 35 82 c1  .............5..
   backtrace:
     [<00000000352f46d8>] kmemleak_alloc_recursive  include/linux/kmemleak.h:43 [inline]
     [<00000000352f46d8>] slab_post_alloc_hook mm/slab.h:522 [inline]
     [<00000000352f46d8>] slab_alloc mm/slab.c:3319 [inline]
     [<00000000352f46d8>] __do_kmalloc mm/slab.c:3653 [inline]
     [<00000000352f46d8>] __kmalloc+0x169/0x300 mm/slab.c:3664
     [<000000008e48f3d1>] kmalloc include/linux/slab.h:557 [inline]
     [<000000008e48f3d1>] ovs_vport_set_upcall_portids+0x54/0xd0  net/openvswitch/vport.c:343
     [<00000000541e4f4a>] ovs_vport_alloc+0x7f/0xf0  net/openvswitch/vport.c:139
     [<00000000f9a04a7d>] internal_dev_create+0x24/0x1d0  net/openvswitch/vport-internal_dev.c:164
     [<0000000056ee7c13>] ovs_vport_add+0x81/0x190  net/openvswitch/vport.c:199
     [<000000005434efc7>] new_vport+0x19/0x80 net/openvswitch/datapath.c:194
     [<00000000b7b253f1>] ovs_dp_cmd_new+0x22f/0x410  net/openvswitch/datapath.c:1614
     [<00000000e0988518>] genl_family_rcv_msg+0x2ab/0x5b0  net/netlink/genetlink.c:629
     [<00000000d0cc9347>] genl_rcv_msg+0x54/0x9c net/netlink/genetlink.c:654
     [<000000006694b647>] netlink_rcv_skb+0x61/0x170  net/netlink/af_netlink.c:2477
     [<0000000088381f37>] genl_rcv+0x29/0x40 net/netlink/genetlink.c:665
     [<00000000dad42a47>] netlink_unicast_kernel  net/netlink/af_netlink.c:1302 [inline]
     [<00000000dad42a47>] netlink_unicast+0x1ec/0x2d0  net/netlink/af_netlink.c:1328
     [<0000000067e6b079>] netlink_sendmsg+0x270/0x480  net/netlink/af_netlink.c:1917
     [<00000000aab08a47>] sock_sendmsg_nosec net/socket.c:637 [inline]
     [<00000000aab08a47>] sock_sendmsg+0x54/0x70 net/socket.c:657
     [<000000004cb7c11d>] ___sys_sendmsg+0x393/0x3c0 net/socket.c:2311
     [<00000000c4901c63>] __sys_sendmsg+0x80/0xf0 net/socket.c:2356

BUG: memory leak
unreferenced object 0xffff8881228ca500 (size 128):
   comm "syz-executor032", pid 7015, jiffies 4294944622 (age 7.880s)
   hex dump (first 32 bytes):
     00 f0 27 18 81 88 ff ff 80 ac 8c 22 81 88 ff ff  ..'........"....
     40 b7 23 17 81 88 ff ff 00 00 00 00 00 00 00 00  @.#.............
   backtrace:
     [<000000000eb78212>] kmemleak_alloc_recursive  include/linux/kmemleak.h:43 [inline]
     [<000000000eb78212>] slab_post_alloc_hook mm/slab.h:522 [inline]
     [<000000000eb78212>] slab_alloc mm/slab.c:3319 [inline]
     [<000000000eb78212>] kmem_cache_alloc_trace+0x145/0x2c0 mm/slab.c:3548
     [<00000000006ea6c6>] kmalloc include/linux/slab.h:552 [inline]
     [<00000000006ea6c6>] kzalloc include/linux/slab.h:748 [inline]
     [<00000000006ea6c6>] ovs_vport_alloc+0x37/0xf0  net/openvswitch/vport.c:130
     [<00000000f9a04a7d>] internal_dev_create+0x24/0x1d0  net/openvswitch/vport-internal_dev.c:164
     [<0000000056ee7c13>] ovs_vport_add+0x81/0x190  net/openvswitch/vport.c:199
     [<000000005434efc7>] new_vport+0x19/0x80 net/openvswitch/datapath.c:194
     [<00000000b7b253f1>] ovs_dp_cmd_new+0x22f/0x410  net/openvswitch/datapath.c:1614
     [<00000000e0988518>] genl_family_rcv_msg+0x2ab/0x5b0  net/netlink/genetlink.c:629
     [<00000000d0cc9347>] genl_rcv_msg+0x54/0x9c net/netlink/genetlink.c:654
     [<000000006694b647>] netlink_rcv_skb+0x61/0x170  net/netlink/af_netlink.c:2477
     [<0000000088381f37>] genl_rcv+0x29/0x40 net/netlink/genetlink.c:665
     [<00000000dad42a47>] netlink_unicast_kernel  net/netlink/af_netlink.c:1302 [inline]
     [<00000000dad42a47>] netlink_unicast+0x1ec/0x2d0  net/netlink/af_netlink.c:1328
     [<0000000067e6b079>] netlink_sendmsg+0x270/0x480  net/netlink/af_netlink.c:1917
     [<00000000aab08a47>] sock_sendmsg_nosec net/socket.c:637 [inline]
     [<00000000aab08a47>] sock_sendmsg+0x54/0x70 net/socket.c:657
     [<000000004cb7c11d>] ___sys_sendmsg+0x393/0x3c0 net/socket.c:2311
     [<00000000c4901c63>] __sys_sendmsg+0x80/0xf0 net/socket.c:2356
     [<00000000c10abb2d>] __do_sys_sendmsg net/socket.c:2365 [inline]
     [<00000000c10abb2d>] __se_sys_sendmsg net/socket.c:2363 [inline]
     [<00000000c10abb2d>] __x64_sys_sendmsg+0x23/0x30 net/socket.c:2363
=====================================================================

The function in net core, register_netdevice(), may fail with vport's
destruction callback either invoked or not. After commit 309b669
("net: openvswitch: do not free vport if register_netdevice() is failed."),
the duty to destroy vport is offloaded from the driver OTOH, which ends
up in the memory leak reported.

It is fixed by releasing vport unless device is registered successfully.
To do that, the callback assignment is defered until device is registered.

Reported-by: [email protected]
Fixes: 309b669 ("net: openvswitch: do not free vport if register_netdevice() is failed.")
Cc: Taehee Yoo <[email protected]>
Cc: Greg Rose <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Marcelo Ricardo Leitner <[email protected]>
Cc: Ying Xue <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Signed-off-by: Hillf Danton <[email protected]>
Acked-by: Pravin B Shelar <[email protected]>
[sbrivio: this was sent to [email protected] and never made its way
 to netdev -- resending original patch]
Signed-off-by: Stefano Brivio <[email protected]>
Reviewed-by: Greg Rose <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Hillf Danton

net/openvswitch/vport-internal_dev.c

@@ -137,7 +137,7 @@ static void do_setup(struct net_device *netdev)
 	netdev->priv_flags |= IFF_LIVE_ADDR_CHANGE | IFF_OPENVSWITCH |
 			      IFF_NO_QUEUE;
 	netdev->needs_free_netdev = true;
-	netdev->priv_destructor = internal_dev_destructor;
+	netdev->priv_destructor = NULL;
 	netdev->ethtool_ops = &internal_dev_ethtool_ops;
 	netdev->rtnl_link_ops = &internal_dev_link_ops;
 
@@ -159,7 +159,6 @@ static struct vport *internal_dev_create(const struct vport_parms *parms)
 	struct internal_dev *internal_dev;
 	struct net_device *dev;
 	int err;
-	bool free_vport = true;
 
 	vport = ovs_vport_alloc(0, &ovs_internal_vport_ops, parms);
 	if (IS_ERR(vport)) {
@@ -190,10 +189,9 @@ static struct vport *internal_dev_create(const struct vport_parms *parms)
 
 	rtnl_lock();
 	err = register_netdevice(vport->dev);
-	if (err) {
-		free_vport = false;
+	if (err)
 		goto error_unlock;
-	}
+	vport->dev->priv_destructor = internal_dev_destructor;
 
 	dev_set_promiscuity(vport->dev, 1);
 	rtnl_unlock();
@@ -207,8 +205,7 @@ static struct vport *internal_dev_create(const struct vport_parms *parms)
 error_free_netdev:
 	free_netdev(dev);
 error_free_vport:
-	if (free_vport)
-		ovs_vport_free(vport);
+	ovs_vport_free(vport);
 error:
 	return ERR_PTR(err);
 }