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Date: Thu, 3 Dec 2020 10:58:21 +0100 From: Davide Caratti <dcaratti@...hat.com> To: Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org Cc: gnault@...hat.com, marcelo.leitner@...il.com, Simon Horman <simon.horman@...ronome.com> Subject: [PATCH net] net: skbuff: ensure LSE is pullable before decrementing the MPLS ttl skb_mpls_dec_ttl() reads the LSE without ensuring that it is contained in the skb "linear" area. Fix this calling pskb_may_pull() before reading the current ttl. Found by code inspection. Fixes: 2a2ea50870ba ("net: sched: add mpls manipulation actions to TC") Reported-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com> Signed-off-by: Davide Caratti <dcaratti@...hat.com> --- net/core/skbuff.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 06c526e0d810..e578544b2cc7 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -5786,6 +5786,9 @@ int skb_mpls_dec_ttl(struct sk_buff *skb) if (unlikely(!eth_p_mpls(skb->protocol))) return -EINVAL; + if (!pskb_may_pull(skb, skb_network_offset(skb) + MPLS_HLEN)) + return -ENOMEM; + lse = be32_to_cpu(mpls_hdr(skb)->label_stack_entry); ttl = (lse & MPLS_LS_TTL_MASK) >> MPLS_LS_TTL_SHIFT; if (!--ttl) -- 2.28.0
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