From patchwork Fri Jun 23 17:18:39 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pauli Virtanen X-Patchwork-Id: 696282 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9D553C001B0 for ; Fri, 23 Jun 2023 17:19:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232394AbjFWRTR (ORCPT ); Fri, 23 Jun 2023 13:19:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47482 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232653AbjFWRS6 (ORCPT ); Fri, 23 Jun 2023 13:18:58 -0400 Received: from lahtoruutu.iki.fi (lahtoruutu.iki.fi [IPv6:2a0b:5c81:1c1::37]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0751E2705 for ; Fri, 23 Jun 2023 10:18:50 -0700 (PDT) Received: from monolith.lan (91-152-120-101.elisa-laajakaista.fi [91.152.120.101]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: pav) by lahtoruutu.iki.fi (Postfix) with ESMTPSA id 4QnkVJ5gVqz49Q8L; Fri, 23 Jun 2023 20:18:48 +0300 (EEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=iki.fi; s=lahtoruutu; t=1687540728; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=w6pae5Alcoqq3vgYCiVKxWEBBEjBOhyN/nu/Ek04sVE=; b=CItbxaXbpDGihECOC2azjAkAcsVDzOWDw4n5Xjk6/PTHcimfKUH2K8Tf/+ZKbpv+IxGzWP UwXInAsRcT1uAT9sHXz/mkgKb+mdsBrzJ5y4LrvpkLwo7vnqw657UELzd7oYS+bk7hcd7J ttWTwY6naS7COoiGKm2DqbMZahtXlAaxNnbY2KAFmJPfH5HwyNLkOsGJ2KXXgGKNwtlhGm Dtkaj0bmagxKYdQhYt8EoNxqJmgjo8yL6BhMWl+vRkubr1EOacMXKw4xKG7qTvAIZ24H8S zzwl1l4RBtPf85BqQ71uXba5QQFJHpaqL9h+ZGquFbV2u0u9A2zKhK/sOManSA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=iki.fi; s=lahtoruutu; t=1687540728; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=w6pae5Alcoqq3vgYCiVKxWEBBEjBOhyN/nu/Ek04sVE=; b=QYfdSWNRbtT170DdAS/OsGOkOW2x4CnPo10Y7LUOwHZHjUQxDy8PlNkZCZgBlsfJuX4aMY CPOYO9Tdbuta8msj57rW6lnzNEGPOi64LpVNIV+P5MXo6pUkZbQOVI62SU03EpbfcTXo+6 uMleiIrgZvGWv/e16cGqeXOy/+Nf+Gfl4BhTRfXQdWp7TMRw8YqOW1C6rPpmTWRvljzuUr inqCCa93pQ/WPUKZj6S/yiJ/sMp7oFDOzjjQXeAZyEhi8aSsU65RiP14YmXN1+5qCX7rsw I9TgkF636xydEpT0ZWhkkSxRaiPZ42BGKc2GBZ/JIXMlFYVEv+NdSu9aYkgxeg== ARC-Authentication-Results: i=1; ORIGINATING; auth=pass smtp.auth=pav smtp.mailfrom=pav@iki.fi ARC-Seal: i=1; s=lahtoruutu; d=iki.fi; t=1687540728; a=rsa-sha256; cv=none; b=BQU7zlPK4s8O/rQybd42AEj6b6edcRHfwfKM7Lwyg4xlYpEtEOXu4zTLZ2eGiR0G0Wb36o JL7mT7HjHsjMU6cekqIxNnEvMW2lOZQlKRpnyX5da6cJoesklRyHFGs2OkLTqJyacuFdlp f7aX12mNuAzl/R+keoodBeIRGpnIxOmxqhIBNsVUuO3tGbH43JzXmz/H2U7FTfEUT1GhvW HZUlF06cr5tKWSJIQH4L3+/dnmotgZckP0EPg8FV9CQN32XGTCy1faPoZe0OEXw2GUNcP3 cgiGOr9v2brH2Dr5VqkoLpNnXK9sXPhf1PMtt0cjRQCfk1oyvxty04a7G5YzDQ== From: Pauli Virtanen To: linux-bluetooth@vger.kernel.org Cc: Pauli Virtanen Subject: [PATCH RFC 2/5] Bluetooth: hci_sync: iterate conn_hash safely in hci_disconnect_all_sync Date: Fri, 23 Jun 2023 20:18:39 +0300 Message-ID: X-Mailer: git-send-email 2.41.0 In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-bluetooth@vger.kernel.org Any element can be removed from conn_hash when no rcu or hdev->lock, so list_for_each_entry_safe alone is not safe here. Add conn_hash iteration that uses RCU and takes hci_conn_get to keep cursors alive, to allow unlocked loop body safely. Since any item may then be deleted from conn_hash while locks are released, in rare cases (next item from cursor deleted) the iteration needs to be restarted. To process each item only once even if restarted, set HCI_CONN_CANCEL in hci_abort_conn_sync, similarly to what hci_abort_conn does. Log trace: ================================================================== BUG: KASAN: slab-use-after-free in hci_set_powered_sync (net/bluetooth/hci_sync.c:5345 net/bluetooth/hci_sync.c:5385 net/bluetooth/hci_sync.c:5397) bluetooth Read of size 8 at addr ffff88800a4d9000 by task kworker/u5:2/966 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014 Workqueue: hci0 hci_cmd_sync_work [bluetooth] Call Trace: dump_stack_lvl (lib/dump_stack.c:108) print_report (mm/kasan/report.c:352 mm/kasan/report.c:462) ? __virt_addr_valid (./include/linux/mmzone.h:1901 ./include/linux/mmzone.h:1997 arch/x86/mm/physaddr.c:65) ? hci_set_powered_sync (net/bluetooth/hci_sync.c:5345 net/bluetooth/hci_sync.c:5385 net/bluetooth/hci_sync.c:5397) bluetooth kasan_report (mm/kasan/report.c:574) ? hci_set_powered_sync (net/bluetooth/hci_sync.c:5345 net/bluetooth/hci_sync.c:5385 net/bluetooth/hci_sync.c:5397) bluetooth hci_set_powered_sync (net/bluetooth/hci_sync.c:5345 net/bluetooth/hci_sync.c:5385 net/bluetooth/hci_sync.c:5397) bluetooth ? __pfx_hci_set_powered_sync (net/bluetooth/hci_sync.c:5393) bluetooth ? set_powered_sync (net/bluetooth/mgmt.c:1369) bluetooth ? __pfx_set_powered_sync (net/bluetooth/mgmt.c:1367) bluetooth hci_cmd_sync_work (net/bluetooth/hci_sync.c:306) bluetooth process_one_work (kernel/workqueue.c:2410) ? __pfx_process_one_work (kernel/workqueue.c:2300) ? __pfx_do_raw_spin_lock (kernel/locking/spinlock_debug.c:113) ? mark_held_locks (kernel/locking/lockdep.c:4240) worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2553) ? __pfx_worker_thread (kernel/workqueue.c:2495) kthread (kernel/kthread.c:379) ? __pfx_kthread (kernel/kthread.c:332) ret_from_fork (arch/x86/entry/entry_64.S:314) Allocated by task 2366: kasan_save_stack (mm/kasan/common.c:46) kasan_set_track (mm/kasan/common.c:52) __kasan_kmalloc (mm/kasan/common.c:374 mm/kasan/common.c:383) hci_conn_add (./include/linux/slab.h:559 ./include/linux/slab.h:680 net/bluetooth/hci_conn.c:1002) bluetooth hci_bind_cis (net/bluetooth/hci_conn.c:1908) bluetooth iso_connect_cis (net/bluetooth/iso.c:383) bluetooth iso_sock_connect (net/bluetooth/iso.c:890) bluetooth __sys_connect (./include/linux/file.h:44 net/socket.c:2021) __x64_sys_connect (net/socket.c:2027) do_syscall_64 (arch/x86/entry/common.c:50 arch/x86/entry/common.c:80) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120) Freed by task 2366: kasan_save_stack (mm/kasan/common.c:46) kasan_set_track (mm/kasan/common.c:52) kasan_save_free_info (mm/kasan/generic.c:523) __kasan_slab_free (mm/kasan/common.c:238 mm/kasan/common.c:200 mm/kasan/common.c:244) __kmem_cache_free (mm/slub.c:1807 mm/slub.c:3786 mm/slub.c:3799) device_release (drivers/base/core.c:2489) kobject_put (lib/kobject.c:683 lib/kobject.c:714 ./include/linux/kref.h:65 lib/kobject.c:731) __iso_sock_close (net/bluetooth/iso.c:665) bluetooth iso_sock_release (net/bluetooth/iso.c:686 net/bluetooth/iso.c:1473) bluetooth __sock_release (net/socket.c:654) sock_close (net/socket.c:1399) __fput (fs/file_table.c:322) task_work_run (kernel/task_work.c:180) exit_to_user_mode_prepare (./include/linux/resume_user_mode.h:49 kernel/entry/common.c:171 kernel/entry/common.c:204) syscall_exit_to_user_mode (kernel/entry/common.c:130 kernel/entry/common.c:299) do_syscall_64 (arch/x86/entry/common.c:87) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:120) ================================================================== Fixes: 182ee45da083 ("Bluetooth: hci_sync: Rework hci_suspend_notifier") Signed-off-by: Pauli Virtanen --- net/bluetooth/hci_sync.c | 140 +++++++++++++++++++++++++++++++++++---- 1 file changed, 127 insertions(+), 13 deletions(-) diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c index afb8e970e62c..46a156b44a8b 100644 --- a/net/bluetooth/hci_sync.c +++ b/net/bluetooth/hci_sync.c @@ -5276,9 +5276,6 @@ static int hci_le_connect_cancel_sync(struct hci_dev *hdev, if (test_bit(HCI_CONN_SCANNING, &conn->flags)) return 0; - if (test_and_set_bit(HCI_CONN_CANCEL, &conn->flags)) - return 0; - return __hci_cmd_sync_status(hdev, HCI_OP_LE_CREATE_CONN_CANCEL, 0, NULL, HCI_CMD_TIMEOUT); } @@ -5334,6 +5331,14 @@ int hci_abort_conn_sync(struct hci_dev *hdev, struct hci_conn *conn, u8 reason) { int err; + /* No hdev->lock: but only accessing dst/type (immutable) and + * state/flags here, in worst case we just send some unnecessary + * HCI commands. + */ + + if (test_and_set_bit(HCI_CONN_CANCEL, &conn->flags)) + return 0; + switch (conn->state) { case BT_CONNECTED: case BT_CONFIG: @@ -5342,10 +5347,12 @@ int hci_abort_conn_sync(struct hci_dev *hdev, struct hci_conn *conn, u8 reason) err = hci_connect_cancel_sync(hdev, conn); /* Cleanup hci_conn object if it cannot be cancelled as it * likelly means the controller and host stack are out of sync. + * Watch out for deleted conn in calling conn_failed. */ if (err) { hci_dev_lock(hdev); - hci_conn_failed(conn, err); + if (hci_conn_is_alive(hdev, conn)) + hci_conn_failed(conn, err); hci_dev_unlock(hdev); } return err; @@ -5359,20 +5366,125 @@ int hci_abort_conn_sync(struct hci_dev *hdev, struct hci_conn *conn, u8 reason) return 0; } -static int hci_disconnect_all_sync(struct hci_dev *hdev, u8 reason) +typedef bool (*hci_conn_iter_func_t)(struct hci_dev *hdev, + struct hci_conn *conn, + void *data); + +/* Iterate connections with unlocked loop body, allowing concurrent mutation, + * holding references to the cursors. If both the cursor and the next item are + * deleted while unlocked, this fails with -EBUSY, or optionally retries + * iteration from start. Note that hci_conn_cleanup may be running concurrently + * or have already completed for the conn, which you need to deal with. + */ +static int hci_conn_hash_list_unlocked(struct hci_dev *hdev, + bool retry, + hci_conn_iter_func_t func, + void *data) { - struct hci_conn *conn, *tmp; - int err; + struct list_head *head = &hdev->conn_hash.list; + struct hci_conn *pos, *prev, *prev_next; - list_for_each_entry_safe(conn, tmp, &hdev->conn_hash.list, list) { - err = hci_abort_conn_sync(hdev, conn, reason); - if (err) - return err; + if (!func) + return 0; + +again: + rcu_read_lock(); + + prev = NULL; + prev_next = NULL; + + pos = list_first_or_null_rcu(head, struct hci_conn, list); + if (pos) + hci_conn_get(pos); + + while (pos) { + struct list_head *ptr = &pos->list; + struct hci_conn *next; + + next = list_next_or_null_rcu(head, ptr, struct hci_conn, list); + if (next) + hci_conn_get(next); + + rcu_read_unlock(); + + /* Can't unref in RCU, so do it here */ + if (prev) { + hci_conn_put(prev); + prev = NULL; + } + + if (prev_next) { + hci_conn_put(prev_next); + prev_next = NULL; + } + + if (func(hdev, pos, data)) { + hci_conn_put(pos); + if (next) + hci_conn_put(next); + + return 0; + } + + rcu_read_lock(); + + if (next && !hci_conn_is_alive(hdev, next)) { + if (!hci_conn_is_alive(hdev, pos)) { + /* Both cursors deleted */ + rcu_read_unlock(); + hci_conn_put(pos); + hci_conn_put(next); + + if (retry) + goto again; + + return -EBUSY; + } + + /* Use the other cursor */ + prev_next = next; + next = list_next_or_null_rcu(head, ptr, + struct hci_conn, list); + if (next) + hci_conn_get(next); + } + + prev = pos; + pos = next; } + rcu_read_unlock(); + + if (prev) + hci_conn_put(prev); + if (prev_next) + hci_conn_put(prev_next); + return 0; } +struct disconnect_all_info { + u8 reason; + int err; +}; + +static bool disconnect_all_sync(struct hci_dev *hdev, struct hci_conn *conn, + void *data) +{ + struct disconnect_all_info *info = data; + + info->err = hci_abort_conn_sync(hdev, conn, info->reason); + return info->err; +} + +static int hci_disconnect_all_sync(struct hci_dev *hdev, u8 reason) +{ + struct disconnect_all_info info = {reason, 0}; + + hci_conn_hash_list_unlocked(hdev, true, disconnect_all_sync, &info); + return info.err; +} + /* This function perform power off HCI command sequence as follows: * * Clear Advertising @@ -6254,8 +6366,10 @@ int hci_le_create_conn_sync(struct hci_dev *hdev, struct hci_conn *conn) conn->conn_timeout, NULL); done: - if (err == -ETIMEDOUT) - hci_le_connect_cancel_sync(hdev, conn); + if (err == -ETIMEDOUT) { + if (!test_and_set_bit(HCI_CONN_CANCEL, &conn->flags)) + hci_le_connect_cancel_sync(hdev, conn); + } /* Re-enable advertising after the connection attempt is finished. */ hci_resume_advertising_sync(hdev);