dccp/tcp: Avoid negative sk_forward_alloc by ipv6_pinfo.pktoptions.
commit ca43ccf41224b023fc290073d5603a755fd12eed upstream. Eric Dumazet pointed out [0] that when we call skb_set_owner_r() for ipv6_pinfo.pktoptions, sk_rmem_schedule() has not been called, resulting in a negative sk_forward_alloc. We add a new helper which clones a skb and sets its owner only when sk_rmem_schedule() succeeds. Note that we move skb_set_owner_r() forward in (dccp|tcp)_v6_do_rcv() because tcp_send_synack() can make sk_forward_alloc negative before ipv6_opt_accepted() in the crossed SYN-ACK or self-connect() cases. [0]: https://lore.kernel.org/netdev/CANn89iK9oc20Jdi_41jb9URdF210r7d1Y-+uypbMSbOfY6jqrg@mail.gmail.com/ Fixes:323fbd0edf
("net: dccp: Add handling of IPV6_PKTOPTIONS to dccp_v6_do_rcv()") Fixes:3df80d9320
("[DCCP]: Introduce DCCPv6") Fixes:1da177e4c3
("Linux-2.6.12-rc2") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Greg Kroah-Hartman

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eb8e9d8572
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@@ -2243,6 +2243,19 @@ static inline __must_check bool skb_set_owner_sk_safe(struct sk_buff *skb, struc
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return false;
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}
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static inline struct sk_buff *skb_clone_and_charge_r(struct sk_buff *skb, struct sock *sk)
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{
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skb = skb_clone(skb, sk_gfp_mask(sk, GFP_ATOMIC));
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if (skb) {
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if (sk_rmem_schedule(sk, skb, skb->truesize)) {
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skb_set_owner_r(skb, sk);
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return skb;
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}
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__kfree_skb(skb);
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}
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return NULL;
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}
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void sk_reset_timer(struct sock *sk, struct timer_list *timer,
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unsigned long expires);
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