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net: avoid infinite loop in mpls_gso_segment when mpls_hlen == 0

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A packet with skb_inner_network_header(skb) == skb_network_header(skb)
and ETH_P_MPLS_UC will prevent mpls_gso_segment from pulling any headers
from the packet. Subsequently, the call to skb_mac_gso_segment will
again call mpls_gso_segment with the same packet leading to an infinite
loop. In addition, ensure that the header length is a multiple of four,
which should hold irrespective of the number of stacked labels.

Signed-off-by: Balazs Nemeth <bnemeth@redhat.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Balazs Nemeth 2021-03-09 12:31:01 +01:00 committed by David S. Miller
parent 924a9bc362
commit d348ede32e
1 changed files with 3 additions and 0 deletions
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3
net/mpls/mpls_gso.c
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@ -14,6 +14,7 @@
#include <linux/netdev_features.h> #include <linux/netdev_features.h>
#include <linux/netdevice.h> #include <linux/netdevice.h>
#include <linux/skbuff.h> #include <linux/skbuff.h>
#include <net/mpls.h>
static struct sk_buff *mpls_gso_segment(struct sk_buff *skb, static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
netdev_features_t features) netdev_features_t features)
@ -27,6 +28,8 @@ static struct sk_buff *mpls_gso_segment(struct sk_buff *skb,
skb_reset_network_header(skb); skb_reset_network_header(skb);
mpls_hlen = skb_inner_network_header(skb) - skb_network_header(skb); mpls_hlen = skb_inner_network_header(skb) - skb_network_header(skb);
if (unlikely(!mpls_hlen || mpls_hlen % MPLS_HLEN))
goto out;
if (unlikely(!pskb_may_pull(skb, mpls_hlen))) if (unlikely(!pskb_may_pull(skb, mpls_hlen)))
goto out; goto out;