4.14-stable review patch. If anyone has any objections, please let me know.
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From: Toshiaki Makita makita.toshiaki@lab.ntt.co.jp
[ Upstream commit c769accdf3d8a103940bea2979b65556718567e9 ]
In some situation vlan packets do not have ethernet headers. One example is packets from tun devices. Users can specify vlan protocol in tun_pi field instead of IP protocol. When we have a vlan device with reorder_hdr disabled on top of the tun device, such packets from tun devices are untagged in skb_vlan_untag() and vlan headers will be inserted back in vlan_insert_inner_tag().
vlan_insert_inner_tag() however did not expect packets without ethernet headers, so in such a case size argument for memmove() underflowed.
We don't need to copy headers for packets which do not have preceding headers of vlan headers, so skip memmove() in that case. Also don't write vlan protocol in skb->data when it does not have enough room for it.
Fixes: cbe7128c4b92 ("vlan: Fix out of order vlan headers 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 --- include/linux/if_vlan.h | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-)
--- a/include/linux/if_vlan.h +++ b/include/linux/if_vlan.h @@ -323,13 +323,24 @@ static inline int __vlan_insert_inner_ta skb_push(skb, VLAN_HLEN);
/* Move the mac header sans proto to the beginning of the new header. */ - memmove(skb->data, skb->data + VLAN_HLEN, mac_len - ETH_TLEN); + if (likely(mac_len > ETH_TLEN)) + memmove(skb->data, skb->data + VLAN_HLEN, mac_len - ETH_TLEN); skb->mac_header -= VLAN_HLEN;
veth = (struct vlan_ethhdr *)(skb->data + mac_len - ETH_HLEN);
/* first, the ethernet type */ - veth->h_vlan_proto = vlan_proto; + if (likely(mac_len >= ETH_TLEN)) { + /* h_vlan_encapsulated_proto should already be populated, and + * skb->data has space for h_vlan_proto + */ + veth->h_vlan_proto = vlan_proto; + } else { + /* h_vlan_encapsulated_proto should not be populated, and + * skb->data has no space for h_vlan_proto + */ + veth->h_vlan_encapsulated_proto = skb->protocol; + }
/* now, the TCI */ veth->h_vlan_TCI = htons(vlan_tci);