Messages in this thread Patch in this message |  | | From | Eric Dumazet <> | Date | Sun, 15 Jan 2023 17:11:48 +0100 | Subject | Re: [PATCH v2 net] tcp: avoid the lookup process failing to get sk in ehash table |
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On Sat, Jan 14, 2023 at 2:27 PM Jason Xing <kerneljasonxing@gmail.com> wrote: > > From: Jason Xing <kernelxing@tencent.com> > > > Fixes: 5e0724d027f0 ("tcp/dccp: fix hashdance race for passive sessions") > Suggested-by: Eric Dumazet <edumazet@google.com> > Signed-off-by: Jason Xing <kernelxing@tencent.com> > Link: https://lore.kernel.org/lkml/20230112065336.41034-1-kerneljasonxing@gmail.com/ > --- > v2: > 1) adding the sk node into the tail of list to prevent the race. > 2) fix the race condition when handling time-wait socket hashdance. > --- > net/ipv4/inet_hashtables.c | 10 ++++++++++ > net/ipv4/inet_timewait_sock.c | 6 +++--- > 2 files changed, 13 insertions(+), 3 deletions(-) > > diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c > index 24a38b56fab9..b0b54ad55507 100644 > --- a/net/ipv4/inet_hashtables.c > +++ b/net/ipv4/inet_hashtables.c > @@ -650,7 +650,16 @@ bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk) > spin_lock(lock); > if (osk) { > WARN_ON_ONCE(sk->sk_hash != osk->sk_hash); > + if (sk_hashed(osk))
nit: this should be:
if (sk_hashed(osk)) { [1] /* multi-line .... * .... comment. */ ret = sk_nulls_del_node_init_rcu(osk); goto unlock; } if (found_dup_sk) { [2]
1) parentheses needed in [1] 2) No else if in [2], since you added a "goto unlock;"
> + /* Before deleting the node, we insert a new one to make > + * sure that the look-up-sk process would not miss either > + * of them and that at least one node would exist in ehash > + * table all the time. Otherwise there's a tiny chance > + * that lookup process could find nothing in ehash table. > + */ > + __sk_nulls_add_node_tail_rcu(sk, list); > ret = sk_nulls_del_node_init_rcu(osk); > + goto unlock; > } else if (found_dup_sk) { > *found_dup_sk = inet_ehash_lookup_by_sk(sk, list); > if (*found_dup_sk) > @@ -660,6 +669,7 @@ bool inet_ehash_insert(struct sock *sk, struct sock *osk, bool *found_dup_sk) > if (ret) > __sk_nulls_add_node_rcu(sk, list); > > +unlock: > spin_unlock(lock);
Thanks.
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