[LLC]: bogus llc packet length

discard llc packet which has bogus packet length.

Signed-off-by: Joonwoo Park <joonwpark81@gmail.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 1 deletions

diff --git a/net/llc/llc_input.c b/net/llc/llc_input.c
index c40c9b2a345a..bfd2567dd365 100644
--- a/net/llc/llc_input.c
+++ b/net/llc/llc_input.c
@@ -117,8 +117,12 @@ static inline int llc_fixup_skb(struct sk_buff *skb)
         skb_pull(skb, llc_len);
         if (skb->protocol == htons(ETH_P_802_2)) {
                 __be16 pdulen = eth_hdr(skb)->h_proto;
-                u16 data_size = ntohs(pdulen) - llc_len;
+                s32 data_size = ntohs(pdulen) - llc_len;
 
+                if (data_size < 0 ||
+                    ((skb_tail_pointer(skb) -
+                      (u8 *)pdu) - llc_len) < data_size)
+                        return 0;
                 if (unlikely(pskb_trim_rcsum(skb, data_size)))
                         return 0;
         }