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From:   Ziyang Xuan <william.xuanziyang@huawei.com>
To:     <dledford@redhat.com>, <jgg@ziepe.ca>
CC:     <leon@kernel.org>, <mbloch@nvidia.com>, <jinpu.wang@ionos.com>,
        <lee.jones@linaro.org>, <linux-rdma@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
Subject: [PATCH rdma-rc] IB/core: fix a UAF for netdev in netdevice_event process
Date:   Mon, 25 Oct 2021 11:42:58 +0800
Message-ID: <20211025034258.2426872-1-william.xuanziyang@huawei.com>
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When a vlan netdev enter netdevice_event process although it is not a
roce netdev, it will be passed to netdevice_event_work_handler() to
process. In order to hold the netdev of netdevice_event after
netdevice_event() return, call dev_hold() to hold the netdev in
netdevice_queue_work(). But that did not consider the real_dev of a vlan
netdev, the real_dev can be freed within netdevice_event_work_handler()
be scheduled. It would trigger the UAF problem for the real_dev like
following:

==================================================================
BUG: KASAN: use-after-free in vlan_dev_real_dev+0xf9/0x120
Read of size 4 at addr ffff88801648a0c4 by task kworker/u8:0/8
Workqueue: gid-cache-wq netdevice_event_work_handler
Call Trace:
 dump_stack_lvl+0xcd/0x134
 print_address_description.constprop.0.cold+0x93/0x334
 kasan_report.cold+0x83/0xdf
 vlan_dev_real_dev+0xf9/0x120
 is_eth_port_of_netdev_filter.part.0+0xb1/0x2c0
 is_eth_port_of_netdev_filter+0x28/0x40
 ib_enum_roce_netdev+0x1a3/0x300
 ib_enum_all_roce_netdevs+0xc7/0x140
 netdevice_event_work_handler+0x9d/0x210
...

Allocated by task 9289:
 kasan_save_stack+0x1b/0x40
 __kasan_kmalloc+0x9b/0xd0
 __kmalloc_node+0x20a/0x330
 kvmalloc_node+0x61/0xf0
 alloc_netdev_mqs+0x9d/0x1140
 rtnl_create_link+0x955/0xb70
 __rtnl_newlink+0xe10/0x15b0
 rtnl_newlink+0x64/0xa0
...

Freed by task 9288:
 kasan_save_stack+0x1b/0x40
 kasan_set_track+0x1c/0x30
 kasan_set_free_info+0x20/0x30
 __kasan_slab_free+0xfc/0x130
 slab_free_freelist_hook+0xdd/0x240
 kfree+0xe4/0x690
 kvfree+0x42/0x50
 device_release+0x9f/0x240
 kobject_put+0x1c8/0x530
 put_device+0x1b/0x30
 free_netdev+0x370/0x540
 ppp_destroy_interface+0x313/0x3d0
 ppp_release+0x1bf/0x240
...

Hold the real_dev for a vlan netdev in netdevice_event_work_handler()
to fix the UAF problem.

Fixes: 238fdf48f2b5 ("IB/core: Add RoCE table bonding support")
Reported-by: syzbot+e4df4e1389e28972e955@syzkaller.appspotmail.com
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
---
 drivers/infiniband/core/roce_gid_mgmt.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/core/roce_gid_mgmt.c b/drivers/infiniband/core/roce_gid_mgmt.c
index 68197e576433..063dbe72b7c2 100644
--- a/drivers/infiniband/core/roce_gid_mgmt.c
+++ b/drivers/infiniband/core/roce_gid_mgmt.c
@@ -621,6 +621,7 @@ static void netdevice_event_work_handler(struct work_struct *_work)
 {
 	struct netdev_event_work *work =
 		container_of(_work, struct netdev_event_work, work);
+	struct net_device *real_dev;
 	unsigned int i;
 
 	for (i = 0; i < ARRAY_SIZE(work->cmds) && work->cmds[i].cb; i++) {
@@ -628,6 +629,12 @@ static void netdevice_event_work_handler(struct work_struct *_work)
 					 work->cmds[i].filter_ndev,
 					 work->cmds[i].cb,
 					 work->cmds[i].ndev);
+		real_dev = rdma_vlan_dev_real_dev(work->cmds[i].ndev);
+		if (real_dev)
+			dev_put(real_dev);
+		real_dev = rdma_vlan_dev_real_dev(work->cmds[i].filter_ndev);
+		if (real_dev)
+			dev_put(real_dev);
 		dev_put(work->cmds[i].ndev);
 		dev_put(work->cmds[i].filter_ndev);
 	}
@@ -638,9 +645,10 @@ static void netdevice_event_work_handler(struct work_struct *_work)
 static int netdevice_queue_work(struct netdev_event_work_cmd *cmds,
 				struct net_device *ndev)
 {
-	unsigned int i;
 	struct netdev_event_work *ndev_work =
 		kmalloc(sizeof(*ndev_work), GFP_KERNEL);
+	struct net_device *real_dev;
+	unsigned int i;
 
 	if (!ndev_work)
 		return NOTIFY_DONE;
@@ -653,6 +661,12 @@ static int netdevice_queue_work(struct netdev_event_work_cmd *cmds,
 			ndev_work->cmds[i].filter_ndev = ndev;
 		dev_hold(ndev_work->cmds[i].ndev);
 		dev_hold(ndev_work->cmds[i].filter_ndev);
+		real_dev = rdma_vlan_dev_real_dev(ndev_work->cmds[i].ndev);
+		if (real_dev)
+			dev_hold(real_dev);
+		real_dev = rdma_vlan_dev_real_dev(ndev_work->cmds[i].filter_ndev);
+		if (real_dev)
+			dev_hold(real_dev);
 	}
 	INIT_WORK(&ndev_work->work, netdevice_event_work_handler);
 
-- 
2.25.1