Commit 4296adc3 authored by Guillaume Nault's avatar Guillaume Nault Committed by David S. Miller

net/core: check length before updating Ethertype in skb_mpls_{push,pop}

Openvswitch allows to drop a packet's Ethernet header, therefore
skb_mpls_push() and skb_mpls_pop() might be called with ethernet=true
and mac_len=0. In that case the pointer passed to skb_mod_eth_type()
doesn't point to an Ethernet header and the new Ethertype is written at
unexpected locations.

Fix this by verifying that mac_len is big enough to contain an Ethernet
header.

Fixes: fa4e0f88 ("net/sched: fix corrupted L2 header with MPLS 'push' and 'pop' actions")
Signed-off-by: default avatarGuillaume Nault <gnault@redhat.com>
Acked-by: default avatarDavide Caratti <dcaratti@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f4544e53
...@@ -5622,7 +5622,7 @@ int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto, ...@@ -5622,7 +5622,7 @@ int skb_mpls_push(struct sk_buff *skb, __be32 mpls_lse, __be16 mpls_proto,
lse->label_stack_entry = mpls_lse; lse->label_stack_entry = mpls_lse;
skb_postpush_rcsum(skb, lse, MPLS_HLEN); skb_postpush_rcsum(skb, lse, MPLS_HLEN);
if (ethernet) if (ethernet && mac_len >= ETH_HLEN)
skb_mod_eth_type(skb, eth_hdr(skb), mpls_proto); skb_mod_eth_type(skb, eth_hdr(skb), mpls_proto);
skb->protocol = mpls_proto; skb->protocol = mpls_proto;
...@@ -5662,7 +5662,7 @@ int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len, ...@@ -5662,7 +5662,7 @@ int skb_mpls_pop(struct sk_buff *skb, __be16 next_proto, int mac_len,
skb_reset_mac_header(skb); skb_reset_mac_header(skb);
skb_set_network_header(skb, mac_len); skb_set_network_header(skb, mac_len);
if (ethernet) { if (ethernet && mac_len >= ETH_HLEN) {
struct ethhdr *hdr; struct ethhdr *hdr;
/* use mpls_hdr() to get ethertype to account for VLANs. */ /* use mpls_hdr() to get ethertype to account for VLANs. */
......
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