[DCCP]: Fix Oops in DCCPv6
I think I got the cause for the Oops observed in http://www.mail-archive.com/dccp@vger.kernel.org/msg00578.html The problem is always with applications listening on PF_INET6 sockets. Apart from the mentioned oops, I observed another one one, triggered at irregular intervals via timer interrupt: run_timer_softirq -> dccp_keepalive_timer -> inet_csk_reqsk_queue_prune -> reqsk_free -> dccp_v6_reqsk_destructor The latter function is the problem and is also the last function to be called in said kernel panic. In any case, there is a real problem with allocating the right request_sock which is what this patch tackles. It fixes the following problem: - application listens on PF_INET6 - DCCPv4 packet comes in, is handed over to dccp_v4_do_rcv, from there to dccp_v4_conn_request Now: socket is PF_INET6, packet is IPv4. The following code then furnishes the connection with IPv6 - request_sock operations: req = reqsk_alloc(sk->sk_prot->rsk_prot); The first problem is that all further incoming packets will get a Reset since the connection can not be looked up. The second problem is worse: --> reqsk_alloc is called instead of inet6_reqsk_alloc --> consequently inet6_rsk_offset is never set (dangling pointer) --> the request_sock_ops are nevertheless still dccp6_request_ops --> destructor is called via reqsk_free --> dccp_v6_reqsk_destructor tries to free random memory location (inet6_rsk_offset not set) --> panic I have tested this for a while, DCCP sockets are now handled correctly in all three scenarios (v4/v6 only/v4-mapped). Commiter note: I've added the dccp_request_sock_ops forward declaration to keep the tree building and to reduce the size of the patch for 2.6.19, later I'll move the functions to the top of the affected source code to match what we have in the TCP counterpart, where this problem hasn't existed in the first place, dumb me not to have done the same thing on DCCP land 8) Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
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@ -449,6 +449,8 @@ static inline u64 dccp_v4_init_sequence(const struct sock *sk,
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dccp_hdr(skb)->dccph_sport);
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}
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static struct request_sock_ops dccp_request_sock_ops;
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int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
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{
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struct inet_request_sock *ireq;
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@ -489,7 +491,7 @@ int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb)
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if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
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goto drop;
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req = reqsk_alloc(sk->sk_prot->rsk_prot);
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req = reqsk_alloc(&dccp_request_sock_ops);
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if (req == NULL)
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goto drop;
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@ -672,7 +672,6 @@ static struct sock *dccp_v6_hnd_req(struct sock *sk,struct sk_buff *skb)
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static int dccp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
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{
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struct inet_request_sock *ireq;
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struct dccp_sock dp;
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struct request_sock *req;
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struct dccp_request_sock *dreq;
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@ -701,7 +700,7 @@ static int dccp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
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if (sk_acceptq_is_full(sk) && inet_csk_reqsk_queue_young(sk) > 1)
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goto drop;
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req = inet6_reqsk_alloc(sk->sk_prot->rsk_prot);
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req = inet6_reqsk_alloc(&dccp6_request_sock_ops);
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if (req == NULL)
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goto drop;
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@ -713,7 +712,6 @@ static int dccp_v6_conn_request(struct sock *sk, struct sk_buff *skb)
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goto drop_and_free;
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ireq6 = inet6_rsk(req);
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ireq = inet_rsk(req);
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ipv6_addr_copy(&ireq6->rmt_addr, &skb->nh.ipv6h->saddr);
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ipv6_addr_copy(&ireq6->loc_addr, &skb->nh.ipv6h->daddr);
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req->rcv_wnd = dccp_feat_default_sequence_window;
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