Re: [PATCH v3 net-next 1/5] net: Get skb hash over flow_keys structure
From: David Miller <davem@davemloft.net>
Date: 2015-05-13 19:30:10
From: Tom Herbert <redacted> Date: Tue, 12 May 2015 08:22:58 -0700
quoted hunk ↗ jump to hunk
@@ -15,6 +15,13 @@ * All the members, except thoff, are in network byte order. */ struct flow_keys { + u16 thoff; + u16 padding1; +#define FLOW_KEYS_HASH_START_FIELD n_proto + __be16 n_proto; + u8 ip_proto; + u8 padding; +
This padding works if everyone consistently zero initializes the whole key structure, but for whatever reason (performance, unintentional oversight, etc.) not all paths do. So, for example, inet_set_txhash() is going to have random crap in keys.padding, so the hashes computed are not stable for a given flow key tuple. That's just the first code path I found with this issue, there are probably several others.