net: skb: check the boundrary of drop reason in kfree_skb_reason()

Sometimes, we may forget to reset skb drop reason to NOT_SPECIFIED after
we make it the return value of the functions with return type of enum
skb_drop_reason, such as tcp_inbound_md5_hash. Therefore, its value can
be SKB_NOT_DROPPED_YET(0), which is invalid for kfree_skb_reason().

So we check the range of drop reason in kfree_skb_reason() with
DEBUG_NET_WARN_ON_ONCE().

Reviewed-by: Jiang Biao <benbjiang@tencent.com>
Reviewed-by: Hao Peng <flyingpeng@tencent.com>
Signed-off-by: Menglong Dong <imagedong@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index bd16e158b3668f496a9d2c8e8b6f3433a326314c..2fea964f09d805268d0f2df2179d17974ca87e74 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -771,6 +771,8 @@ void kfree_skb_reason(struct sk_buff *skb, enum skb_drop_reason reason)
        if (!skb_unref(skb))
                return;
 
+       DEBUG_NET_WARN_ON_ONCE(reason <= 0 || reason >= SKB_DROP_REASON_MAX);
+
        trace_kfree_skb(skb, __builtin_return_address(0), reason);
        __kfree_skb(skb);
 }