diff options
| author | Cong Wang <xiyou.wangcong@gmail.com> | 2017-11-09 16:43:13 -0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-11-11 19:35:32 +0900 |
| commit | 052d41c01b3a2e3371d66de569717353af489d63 (patch) | |
| tree | 995570b6b32fea4c07ac142f608f40c6b2baa9fa | |
| parent | 2118df93b5e1742931da358c2b8804c46fd64490 (diff) | |
vlan: fix a use-after-free in vlan_device_event()
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>
| -rw-r--r-- | net/8021q/vlan.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c index 9649579b5b9f..4a72ee4e2ae9 100644 --- a/net/8021q/vlan.c +++ b/net/8021q/vlan.c @@ -376,6 +376,9 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event, 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 notifier_block *unused, unsigned long event, 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; |