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linux-stable/net/8021q
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Cong Wang 052d41c01b 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: efc73f4bbc ("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>
2017-11-11 19:35:32 +09:00
..
Kconfig 8021q: update description 2014-01-21 17:01:25 -08:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vlan.c vlan: fix a use-after-free in vlan_device_event() 2017-11-11 19:35:32 +09:00
vlan.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vlan_core.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
vlan_dev.c networking: make skb_push & __skb_push return void pointers 2017-06-16 11:48:40 -04:00
vlan_gvrp.c net: vlan: prepare for 802.1ad support 2013-04-19 14:45:27 -04:00
vlan_mvrp.c net: vlan: prepare for 802.1ad support 2013-04-19 14:45:27 -04:00
vlan_netlink.c net: add netlink_ext_ack argument to rtnl_link_ops.validate 2017-06-26 23:13:22 -04:00
vlanproc.c vlan: change return type of vlan_proc_rem_dev 2016-02-17 22:06:28 -05:00
vlanproc.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00