From 8baa52f26b3e3817ab25955653930590e6e6b6c9 Mon Sep 17 00:00:00 2001 From: Balazs Nemeth Date: Tue, 9 Mar 2021 12:31:01 +0100 Subject: [PATCH] net: avoid infinite loop in mpls_gso_segment when mpls_hlen == 0 commit d348ede32e99d3a04863e9f9b28d224456118c27 upstream. 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 Acked-by: Willem de Bruijn Reviewed-by: David Ahern Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/mpls/mpls_gso.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/mpls/mpls_gso.c b/net/mpls/mpls_gso.c index b1690149b6fa..1482259de9b5 100644 --- a/net/mpls/mpls_gso.c +++ b/net/mpls/mpls_gso.c @@ -14,6 +14,7 @@ #include #include #include +#include static struct sk_buff *mpls_gso_segment(struct sk_buff *skb, netdev_features_t features) @@ -27,6 +28,8 @@ static struct sk_buff *mpls_gso_segment(struct sk_buff *skb, skb_reset_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))) goto out;