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[79.191.186.228]) by smtp.gmail.com with ESMTPSA id n23sm22905586wmc.38.2021.07.21.09.36.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 21 Jul 2021 09:36:24 -0700 (PDT) References: <20210719214834.125484-1-john.fastabend@gmail.com> <20210719214834.125484-4-john.fastabend@gmail.com> User-agent: mu4e 1.1.0; emacs 27.2 From: Jakub Sitnicki To: John Fastabend Cc: daniel@iogearbox.net, xiyou.wangcong@gmail.com, alexei.starovoitov@gmail.com, bpf@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH bpf 3/3] bpf, sockmap: fix memleak on ingress msg enqueue In-reply-to: <20210719214834.125484-4-john.fastabend@gmail.com> Date: Wed, 21 Jul 2021 18:36:23 +0200 Message-ID: <87sg07r5dk.fsf@cloudflare.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Mon, Jul 19, 2021 at 11:48 PM CEST, John Fastabend wrote: > If backlog handler is running during a tear down operation we may enqueue > data on the ingress msg queue while tear down is trying to free it. > > sk_psock_backlog() > sk_psock_handle_skb() > skb_psock_skb_ingress() > sk_psock_skb_ingress_enqueue() > sk_psock_queue_msg(psock,msg) > spin_lock(ingress_lock) > sk_psock_zap_ingress() > _sk_psock_purge_ingerss_msg() > _sk_psock_purge_ingress_msg() > -- free ingress_msg list -- > spin_unlock(ingress_lock) > spin_lock(ingress_lock) > list_add_tail(msg,ingress_msg) <- entry on list with no on > left to free it. > spin_unlock(ingress_lock) > > To fix we only enqueue from backlog if the ENABLED bit is set. The tear > down logic clears the bit with ingress_lock set so we wont enqueue the > msg in the last step. > > Fixes: 799aa7f98d53 ("skmsg: Avoid lock_sock() in sk_psock_backlog()") > Signed-off-by: John Fastabend > --- > include/linux/skmsg.h | 54 ++++++++++++++++++++++++++++--------------- > net/core/skmsg.c | 6 ----- > 2 files changed, 35 insertions(+), 25 deletions(-) > > diff --git a/include/linux/skmsg.h b/include/linux/skmsg.h > index 96f319099744..883638888f93 100644 > --- a/include/linux/skmsg.h > +++ b/include/linux/skmsg.h > @@ -285,11 +285,45 @@ static inline struct sk_psock *sk_psock(const struct sock *sk) > return rcu_dereference_sk_user_data(sk); > } > > +static inline void sk_psock_set_state(struct sk_psock *psock, > + enum sk_psock_state_bits bit) > +{ > + set_bit(bit, &psock->state); > +} > + > +static inline void sk_psock_clear_state(struct sk_psock *psock, > + enum sk_psock_state_bits bit) > +{ > + clear_bit(bit, &psock->state); > +} > + > +static inline bool sk_psock_test_state(const struct sk_psock *psock, > + enum sk_psock_state_bits bit) > +{ > + return test_bit(bit, &psock->state); > +} > + > +static void sock_drop(struct sock *sk, struct sk_buff *skb) > +{ > + sk_drops_add(sk, skb); > + kfree_skb(skb); > +} > + > +static inline void drop_sk_msg(struct sk_psock *psock, struct sk_msg *msg) > +{ > + if (msg->skb) > + sock_drop(psock->sk, msg->skb); > + kfree(msg); > +} > + > static inline void sk_psock_queue_msg(struct sk_psock *psock, > struct sk_msg *msg) > { > spin_lock_bh(&psock->ingress_lock); > - list_add_tail(&msg->list, &psock->ingress_msg); > + if (sk_psock_test_state(psock, SK_PSOCK_TX_ENABLED)) Whitespace issue ^. Otherwise LGTM. > + list_add_tail(&msg->list, &psock->ingress_msg); > + else > + drop_sk_msg(psock, msg); > spin_unlock_bh(&psock->ingress_lock); > } > [...]