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 <[email protected]>
Signed-off-by: Davide Caratti <[email protected]>
---
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
