diff options
| author | David S. Miller <davem@davemloft.net> | 2018-03-30 12:36:28 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-03-30 12:36:28 -0400 |
| commit | 52a9692a43b8cbca179d2dd02e714df6f1197932 (patch) | |
| tree | 67df9144cea6262fc7660a1c8cc0556df7bf0a8b | |
| parent | a9645b273e22662ebea563eae334eb3e4fc6614e (diff) | |
| parent | c769accdf3d8a103940bea2979b65556718567e9 (diff) | |
Merge branch 'vlan-fix'
Toshiaki Makita says:
====================
Fix vlan tag handling for vlan packets without ethernet headers
Eric Dumazet reported syzbot found a new bug which leads to underflow of
size argument of memmove(), causing crash[1]. This can be triggered by tun
devices.
The underflow happened because skb_vlan_untag() did not expect vlan packets
without ethernet headers, and tun can produce such packets.
I also checked vlan_insert_inner_tag() and found a similar bug.
This series fixes these problems.
[1] https://marc.info/?l=linux-netdev&m=152221753920510&w=2
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | include/linux/if_vlan.h | 15 | ||||
| -rw-r--r-- | net/core/skbuff.c | 6 |
2 files changed, 17 insertions, 4 deletions
diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h index c4a1cff9c768..7d30892da064 100644 --- a/include/linux/if_vlan.h +++ b/include/linux/if_vlan.h @@ -323,13 +323,24 @@ static inline int __vlan_insert_inner_tag(struct sk_buff *skb, 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); diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 1e7acdc30732..857e4e6f751a 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -5028,8 +5028,10 @@ static struct sk_buff *skb_reorder_vlan_header(struct sk_buff *skb) } mac_len = skb->data - skb_mac_header(skb); - memmove(skb_mac_header(skb) + VLAN_HLEN, skb_mac_header(skb), - mac_len - VLAN_HLEN - ETH_TLEN); + if (likely(mac_len > VLAN_HLEN + ETH_TLEN)) { + memmove(skb_mac_header(skb) + VLAN_HLEN, skb_mac_header(skb), + mac_len - VLAN_HLEN - ETH_TLEN); + } skb->mac_header += VLAN_HLEN; return skb; } |