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Toshiaki Makita
01a68a265e
[ Upstream commit4bbb3e0e82] When we have a bridge with vlan_filtering on and a vlan device on top of it, packets would be corrupted in skb_vlan_untag() called from br_dev_xmit(). The problem sits in skb_reorder_vlan_header() used in skb_vlan_untag(), which makes use of skb->mac_len. In this function mac_len is meant for handling rx path with vlan devices with reorder_header disabled, but in tx path mac_len is typically 0 and cannot be used, which is the problem in this case. The current code even does not properly handle rx path (skb_vlan_untag() called from __netif_receive_skb_core()) with reorder_header off actually. In rx path single tag case, it works as follows: - Before skb_reorder_vlan_header() mac_header data v v +-------------------+-------------+------+---- | ETH | VLAN | ETH | | ADDRS | TPID | TCI | TYPE | +-------------------+-------------+------+---- <-------- mac_len ---------> <-------------> to be removed - After skb_reorder_vlan_header() mac_header data v v +-------------------+------+---- | ETH | ETH | | ADDRS | TYPE | +-------------------+------+---- <-------- mac_len ---------> This is ok, but in rx double tag case, it corrupts packets: - Before skb_reorder_vlan_header() mac_header data v v +-------------------+-------------+-------------+------+---- | ETH | VLAN | VLAN | ETH | | ADDRS | TPID | TCI | TPID | TCI | TYPE | +-------------------+-------------+-------------+------+---- <--------------- mac_len ----------------> <-------------> should be removed <---------------------------> actually will be removed - After skb_reorder_vlan_header() mac_header data v v +-------------------+------+---- | ETH | ETH | | ADDRS | TYPE | +-------------------+------+---- <--------------- mac_len ----------------> So, two of vlan tags are both removed while only inner one should be removed and mac_header (and mac_len) is broken. skb_vlan_untag() is meant for removing the vlan header at (skb->data - 2), so use skb->data and skb->mac_header to calculate the right offset. Reported-by: Brandon Carpenter <brandon.carpenter@cypherpath.com> Fixes:a6e18ff111("vlan: Fix untag operations of stacked vlans with REORDER_HEADER off") Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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