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net: openvswitch: ensure LSE is pullable before reading it

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when openvswitch is configured to mangle the LSE, the current value is
read from the packet dereferencing 4 bytes at mpls_hdr(): ensure that
the label is contained in the skb "linear" area.

Found by code inspection.

Fixes: d27cf5c59a ("net: core: add MPLS update core helper and use in OvS")
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Link: https://lore.kernel.org/r/aa099f245d93218b84b5c056b67b6058ccf81a66.1606987185.git.dcaratti@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Davide Caratti 2020-12-03 10:46:06 +01:00 committed by Jakub Kicinski
parent 13de4ed9e3
commit 43c13605ba
1 changed files with 3 additions and 0 deletions
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3
net/openvswitch/actions.c
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@ -199,6 +199,9 @@ static int set_mpls(struct sk_buff *skb, struct sw_flow_key *flow_key,
__be32 lse;
int err;
if (!pskb_may_pull(skb, skb_network_offset(skb) + MPLS_HLEN))
return -ENOMEM;
stack = mpls_hdr(skb);
lse = OVS_MASKED(stack->label_stack_entry, *mpls_lse, *mask);
err = skb_mpls_update_lse(skb, lse);