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[144.76.156.219]) by smtp.gmail.com with ESMTPSA id ax39-20020a05687c022700b0016b0369f08fsm7351116oac.15.2023.03.09.06.50.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Mar 2023 06:50:51 -0800 (PST) From: Matthieu Baerts Date: Thu, 09 Mar 2023 15:50:00 +0100 Subject: [PATCH net v2 4/8] mptcp: fix UaF in listener shutdown Precedence: bulk X-Mailing-List: mptcp@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20230227-upstream-net-20230227-mptcp-fixes-v2-4-47c2e95eada9@tessares.net> References: <20230227-upstream-net-20230227-mptcp-fixes-v2-0-47c2e95eada9@tessares.net> In-Reply-To: <20230227-upstream-net-20230227-mptcp-fixes-v2-0-47c2e95eada9@tessares.net> To: mptcp@lists.linux.dev, "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Mat Martineau , Jiang Biao , Menglong Dong , Mengen Sun , Shuah Khan , Florian Westphal Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Matthieu Baerts , stable@vger.kernel.org, Christoph Paasch X-Mailer: b4 0.12.1 X-Developer-Signature: v=1; a=openpgp-sha256; l=6328; i=matthieu.baerts@tessares.net; h=from:subject:message-id; bh=TJIewReJ/yOGpWt8keCbB5zXjaxYZOxSV1Zl9q3p0x0=; b=owEBbQKS/ZANAwAIAfa3gk9CaaBzAcsmYgBkCfIhBXsVeZCD4caj3mT+fPvYXxeBAkoAALrYI VKKDez3LnaJAjMEAAEIAB0WIQToy4X3aHcFem4n93r2t4JPQmmgcwUCZAnyIQAKCRD2t4JPQmmg c434D/4ikPybhwE5pZT5G2x9W5cfhIZMvjQZCPWoFP/zVpZzEwfsvhO9MrQJWFYQp7MvVYoAQTb eaRCqSZ+A2wTz5lTrEncsw8gy9/HpkActlxZd+FDGQtzC62dOaSjfDrlorYTwRfSRlPNxTotccl mYqyZ4lypkVi33xZ4HjoJCEfrG9s7l6UYMB7tD8LW4Dpq2MmIxhO/YfWwTa+ZMhv8beOQLP2JdR wIk+4h/h6DP8amWByt6W0YwCjf9Uv5T2s1NdpQiB5oD/5KJVSeB0jWZeTi9Tx5aeuYP7YC1NrLK xL10fq7FUkBuYaxK/IrZCUx4Dtu02utlbIqdW9ikCiQ4PYqsyFsXqMxTEFklkg+MqqEnldZA6K0 5JtD+pvuxHnGxmZc0R8Dw5CXS/2k1fYWcRNcIabqA5LNnq/UNJctAYX6RUTkWMEXXANT6QzSMXc sbGfPwtdihdqt9qkJtCC1Y2BUlxPOwpvPM9p4EF0Y3roAfCMFTmC+wm5MqzXPYqL+ls19+/UsIs ziaYhAG2T4VNHjUVMRQSFHZtSaD+kMuBbFI06CQxvXmkD2XA6TamC7G5D1EMcZx/mOqz7x9oxFt YmJRKONECgBspQvh4DkBigKPENXh76Jc1jWQre0P1rK9udR/M17ZvDDbSr3o9N8a6h8LNnKfhqn 3bFby3ULhxVe1oQ== X-Developer-Key: i=matthieu.baerts@tessares.net; a=openpgp; fpr=E8CB85F76877057A6E27F77AF6B7824F4269A073 From: Paolo Abeni As reported by Christoph after having refactored the passive socket initialization, the mptcp listener shutdown path is prone to an UaF issue. BUG: KASAN: use-after-free in _raw_spin_lock_bh+0x73/0xe0 Write of size 4 at addr ffff88810cb23098 by task syz-executor731/1266 CPU: 1 PID: 1266 Comm: syz-executor731 Not tainted 6.2.0-rc59af4eaa31c1f6= c00c8f1e448ed99a45c66340dd5 #6 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-= gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 Call Trace: dump_stack_lvl+0x6e/0x91 print_report+0x16a/0x46f kasan_report+0xad/0x130 kasan_check_range+0x14a/0x1a0 _raw_spin_lock_bh+0x73/0xe0 subflow_error_report+0x6d/0x110 sk_error_report+0x3b/0x190 tcp_disconnect+0x138c/0x1aa0 inet_child_forget+0x6f/0x2e0 inet_csk_listen_stop+0x209/0x1060 __mptcp_close_ssk+0x52d/0x610 mptcp_destroy_common+0x165/0x640 mptcp_destroy+0x13/0x80 __mptcp_destroy_sock+0xe7/0x270 __mptcp_close+0x70e/0x9b0 mptcp_close+0x2b/0x150 inet_release+0xe9/0x1f0 __sock_release+0xd2/0x280 sock_close+0x15/0x20 __fput+0x252/0xa20 task_work_run+0x169/0x250 exit_to_user_mode_prepare+0x113/0x120 syscall_exit_to_user_mode+0x1d/0x40 do_syscall_64+0x48/0x90 entry_SYSCALL_64_after_hwframe+0x72/0xdc The msk grace period can legitly expire in between the last reference count dropped in mptcp_subflow_queue_clean() and the later eventual access in inet_csk_listen_stop() After the previous patch we don't need anymore special-casing msk listener socket cleanup: the mptcp worker will process each of the unaccepted msk sockets. Just drop the now unnecessary code. Please note this commit depends on the two parent ones: mptcp: refactor passive socket initialization mptcp: use the workqueue to destroy unaccepted sockets Fixes: 6aeed9045071 ("mptcp: fix race on unaccepted mptcp sockets") Cc: stable@vger.kernel.org Reported-and-tested-by: Christoph Paasch Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/346 Signed-off-by: Paolo Abeni Reviewed-by: Matthieu Baerts Signed-off-by: Matthieu Baerts --- net/mptcp/protocol.c | 7 ++--- net/mptcp/protocol.h | 1 - net/mptcp/subflow.c | 72 ------------------------------------------------= ---- 3 files changed, 2 insertions(+), 78 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index 2a2093d61835..60b23b2716c4 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2365,12 +2365,9 @@ static void __mptcp_close_ssk(struct sock *sk, struc= t sock *ssk, mptcp_subflow_drop_ctx(ssk); } else { /* otherwise tcp will dispose of the ssk and subflow ctx */ - if (ssk->sk_state =3D=3D TCP_LISTEN) { - tcp_set_state(ssk, TCP_CLOSE); - mptcp_subflow_queue_clean(sk, ssk); - inet_csk_listen_stop(ssk); + if (ssk->sk_state =3D=3D TCP_LISTEN) mptcp_event_pm_listener(ssk, MPTCP_EVENT_LISTENER_CLOSED); - } + __tcp_close(ssk, 0); =20 /* close acquired an extra ref */ diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 3a2db1b862dd..339a6f072989 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -629,7 +629,6 @@ void mptcp_close_ssk(struct sock *sk, struct sock *ssk, struct mptcp_subflow_context *subflow); void __mptcp_subflow_send_ack(struct sock *ssk); void mptcp_subflow_reset(struct sock *ssk); -void mptcp_subflow_queue_clean(struct sock *sk, struct sock *ssk); void mptcp_sock_graft(struct sock *sk, struct socket *parent); struct socket *__mptcp_nmpc_socket(const struct mptcp_sock *msk); bool __mptcp_close(struct sock *sk, long timeout); diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index 932a3e0eb22d..9c57575df84c 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1826,78 +1826,6 @@ static void subflow_state_change(struct sock *sk) } } =20 -void mptcp_subflow_queue_clean(struct sock *listener_sk, struct sock *list= ener_ssk) -{ - struct request_sock_queue *queue =3D &inet_csk(listener_ssk)->icsk_accept= _queue; - struct mptcp_sock *msk, *next, *head =3D NULL; - struct request_sock *req; - - /* build a list of all unaccepted mptcp sockets */ - spin_lock_bh(&queue->rskq_lock); - for (req =3D queue->rskq_accept_head; req; req =3D req->dl_next) { - struct mptcp_subflow_context *subflow; - struct sock *ssk =3D req->sk; - struct mptcp_sock *msk; - - if (!sk_is_mptcp(ssk)) - continue; - - subflow =3D mptcp_subflow_ctx(ssk); - if (!subflow || !subflow->conn) - continue; - - /* skip if already in list */ - msk =3D mptcp_sk(subflow->conn); - if (msk->dl_next || msk =3D=3D head) - continue; - - msk->dl_next =3D head; - head =3D msk; - } - spin_unlock_bh(&queue->rskq_lock); - if (!head) - return; - - /* can't acquire the msk socket lock under the subflow one, - * or will cause ABBA deadlock - */ - release_sock(listener_ssk); - - for (msk =3D head; msk; msk =3D next) { - struct sock *sk =3D (struct sock *)msk; - bool do_cancel_work; - - lock_sock_nested(sk, SINGLE_DEPTH_NESTING); - next =3D msk->dl_next; - msk->first =3D NULL; - msk->dl_next =3D NULL; - - do_cancel_work =3D __mptcp_close(sk, 0); - release_sock(sk); - if (do_cancel_work) { - /* lockdep will report a false positive ABBA deadlock - * between cancel_work_sync and the listener socket. - * The involved locks belong to different sockets WRT - * the existing AB chain. - * Using a per socket key is problematic as key - * deregistration requires process context and must be - * performed at socket disposal time, in atomic - * context. - * Just tell lockdep to consider the listener socket - * released here. - */ - mutex_release(&listener_sk->sk_lock.dep_map, _RET_IP_); - mptcp_cancel_work(sk); - mutex_acquire(&listener_sk->sk_lock.dep_map, - SINGLE_DEPTH_NESTING, 0, _RET_IP_); - } - sock_put(sk); - } - - /* we are still under the listener msk socket lock */ - lock_sock_nested(listener_ssk, SINGLE_DEPTH_NESTING); -} - static int subflow_ulp_init(struct sock *sk) { struct inet_connection_sock *icsk =3D inet_csk(sk); --=20 2.39.2