This is a note to let you know that I've just added the patch titled

vlan: fix a use-after-free in vlan_device_event()

to the 4.13-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: vlan-fix-a-use-after-free-in-vlan_device_event.patch and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Tue Nov 21 13:07:20 CET 2017

From: Cong Wang xiyou.wangcong@gmail.com Date: Thu, 9 Nov 2017 16:43:13 -0800 Subject: vlan: fix a use-after-free in vlan_device_event()

From: Cong Wang xiyou.wangcong@gmail.com

[ Upstream commit 052d41c01b3a2e3371d66de569717353af489d63 ]

After refcnt reaches zero, vlan_vid_del() could free dev->vlan_info via RCU:

RCU_INIT_POINTER(dev->vlan_info, NULL); call_rcu(&vlan_info->rcu, vlan_info_rcu_free);

However, the pointer 'grp' still points to that memory since it is set before vlan_vid_del():

vlan_info = rtnl_dereference(dev->vlan_info); if (!vlan_info) goto out; grp = &vlan_info->grp;

Depends on when that RCU callback is scheduled, we could trigger a use-after-free in vlan_group_for_each_dev() right following this vlan_vid_del().

Fix it by moving vlan_vid_del() before setting grp. This is also symmetric to the vlan_vid_add() we call in vlan_device_event().

Reported-by: Fengguang Wu fengguang.wu@intel.com Fixes: efc73f4bbc23 ("net: Fix memory leak - vlan_info struct") Cc: Alexander Duyck alexander.duyck@gmail.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Girish Moodalbail girish.moodalbail@oracle.com Signed-off-by: Cong Wang xiyou.wangcong@gmail.com Reviewed-by: Girish Moodalbail girish.moodalbail@oracle.com Tested-by: Fengguang Wu fengguang.wu@intel.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/8021q/vlan.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/net/8021q/vlan.c +++ b/net/8021q/vlan.c @@ -376,6 +376,9 @@ static int vlan_device_event(struct noti dev->name); vlan_vid_add(dev, htons(ETH_P_8021Q), 0); } + if (event == NETDEV_DOWN && + (dev->features & NETIF_F_HW_VLAN_CTAG_FILTER)) + vlan_vid_del(dev, htons(ETH_P_8021Q), 0);

vlan_info = rtnl_dereference(dev->vlan_info); if (!vlan_info) @@ -423,9 +426,6 @@ static int vlan_device_event(struct noti struct net_device *tmp; LIST_HEAD(close_list);

- if (dev->features & NETIF_F_HW_VLAN_CTAG_FILTER) - vlan_vid_del(dev, htons(ETH_P_8021Q), 0); - /* Put all VLANs for this dev in the down state too. */ vlan_group_for_each_dev(grp, i, vlandev) { flgs = vlandev->flags;

Patches currently in stable-queue which might be from xiyou.wangcong@gmail.com are

queue-4.13/vlan-fix-a-use-after-free-in-vlan_device_event.patch