From fa78d2d1d64f147062e384a4a10a26a5f89944b5 Mon Sep 17 00:00:00 2001 From: Lin Ma Date: Wed, 16 Feb 2022 12:37:14 +0800 Subject: Bluetooth: fix data races in smp_unregister(), smp_del_chan() Previous commit e04480920d1e ("Bluetooth: defer cleanup of resources in hci_unregister_dev()") defers all destructive actions to hci_release_dev() to prevent cocurrent problems like NPD, UAF. However, there are still some exceptions that are ignored. The smp_unregister() in hci_dev_close_sync() (previously in hci_dev_do_close) will release resources like the sensitive channel and the smp_dev objects. Consider the situations the device is detaching or power down while the kernel is still operating on it, the following data race could take place. thread-A hci_dev_close_sync | thread-B read_local_oob_ext_data | hci_dev_unlock() | ... | hci_dev_lock() if (hdev->smp_data) | chan = hdev->smp_data | | chan = hdev->smp_data (3) | hdev->smp_data = NULL (1) | if (!chan || !chan->data) (4) ... | smp = chan->data | smp = chan->data if (smp) | chan->data = NULL (2) | ... | kfree_sensitive(smp) | | // dereference smp trigger UFA That is, the objects hdev->smp_data and chan->data both suffer from the data races. In a preempt-enable kernel, the above schedule (when (3) is before (1) and (4) is before (2)) leads to UAF bugs. It can be reproduced in the latest kernel and below is part of the report: [ 49.097146] ================================================================ [ 49.097611] BUG: KASAN: use-after-free in smp_generate_oob+0x2dd/0x570 [ 49.097611] Read of size 8 at addr ffff888006528360 by task generate_oob/155 [ 49.097611] [ 49.097611] Call Trace: [ 49.097611] [ 49.097611] dump_stack_lvl+0x34/0x44 [ 49.097611] print_address_description.constprop.0+0x1f/0x150 [ 49.097611] ? smp_generate_oob+0x2dd/0x570 [ 49.097611] ? smp_generate_oob+0x2dd/0x570 [ 49.097611] kasan_report.cold+0x7f/0x11b [ 49.097611] ? smp_generate_oob+0x2dd/0x570 [ 49.097611] smp_generate_oob+0x2dd/0x570 [ 49.097611] read_local_oob_ext_data+0x689/0xc30 [ 49.097611] ? hci_event_packet+0xc80/0xc80 [ 49.097611] ? sysvec_apic_timer_interrupt+0x9b/0xc0 [ 49.097611] ? asm_sysvec_apic_timer_interrupt+0x12/0x20 [ 49.097611] ? mgmt_init_hdev+0x1c/0x240 [ 49.097611] ? mgmt_init_hdev+0x28/0x240 [ 49.097611] hci_sock_sendmsg+0x1880/0x1e70 [ 49.097611] ? create_monitor_event+0x890/0x890 [ 49.097611] ? create_monitor_event+0x890/0x890 [ 49.097611] sock_sendmsg+0xdf/0x110 [ 49.097611] __sys_sendto+0x19e/0x270 [ 49.097611] ? __ia32_sys_getpeername+0xa0/0xa0 [ 49.097611] ? kernel_fpu_begin_mask+0x1c0/0x1c0 [ 49.097611] __x64_sys_sendto+0xd8/0x1b0 [ 49.097611] ? syscall_exit_to_user_mode+0x1d/0x40 [ 49.097611] do_syscall_64+0x3b/0x90 [ 49.097611] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 49.097611] RIP: 0033:0x7f5a59f51f64 ... [ 49.097611] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f5a59f51f64 [ 49.097611] RDX: 0000000000000007 RSI: 00007f5a59d6ac70 RDI: 0000000000000006 [ 49.097611] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 49.097611] R10: 0000000000000040 R11: 0000000000000246 R12: 00007ffec26916ee [ 49.097611] R13: 00007ffec26916ef R14: 00007f5a59d6afc0 R15: 00007f5a59d6b700 To solve these data races, this patch places the smp_unregister() function in the protected area by the hci_dev_lock(). That is, the smp_unregister() function can not be concurrently executed when operating functions (most of them are mgmt operations in mgmt.c) hold the device lock. This patch is tested with kernel LOCK DEBUGGING enabled. The price from the extended holding time of the device lock is supposed to be low as the smp_unregister() function is fairly short and efficient. Signed-off-by: Lin Ma Signed-off-by: Marcel Holtmann --- net/bluetooth/hci_sync.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'net/bluetooth/hci_sync.c') diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c index 0feb68f12545..e34fc15b7d2c 100644 --- a/net/bluetooth/hci_sync.c +++ b/net/bluetooth/hci_sync.c @@ -4106,9 +4106,9 @@ int hci_dev_close_sync(struct hci_dev *hdev) hci_inquiry_cache_flush(hdev); hci_pend_le_actions_clear(hdev); hci_conn_hash_flush(hdev); - hci_dev_unlock(hdev); - + /* Prevent data races on hdev->smp_data or hdev->smp_bredr_data */ smp_unregister(hdev); + hci_dev_unlock(hdev); hci_sock_dev_event(hdev, HCI_DEV_DOWN); -- cgit v1.2.3-70-g09d2 From 80740ebb7e1ad15ab9c11425dcd26e073f86d74b Mon Sep 17 00:00:00 2001 From: Luiz Augusto von Dentz Date: Thu, 24 Feb 2022 07:11:47 -0800 Subject: Bluetooth: hci_sync: Fix hci_update_accept_list_sync hci_update_accept_list_sync is returning the filter based on the error but that gets overwritten by hci_le_set_addr_resolution_enable_sync return instead of using the actual result of the likes of hci_le_add_accept_list_sync which was intended. Fixes: ad383c2c65a5b ("Bluetooth: hci_sync: Enable advertising when LL privacy is enabled") Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Marcel Holtmann --- net/bluetooth/hci_sync.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'net/bluetooth/hci_sync.c') diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c index e34fc15b7d2c..9d8490570b42 100644 --- a/net/bluetooth/hci_sync.c +++ b/net/bluetooth/hci_sync.c @@ -1841,6 +1841,7 @@ static u8 hci_update_accept_list_sync(struct hci_dev *hdev) struct bdaddr_list *b, *t; u8 num_entries = 0; bool pend_conn, pend_report; + u8 filter_policy; int err; /* Pause advertising if resolving list can be used as controllers are @@ -1927,6 +1928,8 @@ static u8 hci_update_accept_list_sync(struct hci_dev *hdev) err = -EINVAL; done: + filter_policy = err ? 0x00 : 0x01; + /* Enable address resolution when LL Privacy is enabled. */ err = hci_le_set_addr_resolution_enable_sync(hdev, 0x01); if (err) @@ -1937,7 +1940,7 @@ done: hci_resume_advertising_sync(hdev); /* Select filter policy to use accept list */ - return err ? 0x00 : 0x01; + return filter_policy; } /* Returns true if an le connection is in the scanning state */ -- cgit v1.2.3-70-g09d2 From a56a1138cbd85e4d565356199d60e1cb94e5a77a Mon Sep 17 00:00:00 2001 From: Luiz Augusto von Dentz Date: Thu, 17 Feb 2022 13:10:38 -0800 Subject: Bluetooth: hci_sync: Fix not using conn_timeout When using hci_le_create_conn_sync it shall wait for the conn_timeout since the connection complete may take longer than just 2 seconds. Also fix the masking of HCI_EV_LE_ENHANCED_CONN_COMPLETE and HCI_EV_LE_CONN_COMPLETE so they are never both set so we can predict which one the controller will use in case of HCI_OP_LE_CREATE_CONN. Fixes: 6cd29ec6ae5e3 ("Bluetooth: hci_sync: Wait for proper events when connecting LE") Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Marcel Holtmann --- include/net/bluetooth/hci_core.h | 8 ++++++++ net/bluetooth/hci_sync.c | 21 +++++++++++++++------ 2 files changed, 23 insertions(+), 6 deletions(-) (limited to 'net/bluetooth/hci_sync.c') diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h index 586f69d084a2..e336e9c1dda4 100644 --- a/include/net/bluetooth/hci_core.h +++ b/include/net/bluetooth/hci_core.h @@ -1489,6 +1489,14 @@ void hci_conn_del_sysfs(struct hci_conn *conn); /* Extended advertising support */ #define ext_adv_capable(dev) (((dev)->le_features[1] & HCI_LE_EXT_ADV)) +/* BLUETOOTH CORE SPECIFICATION Version 5.3 | Vol 4, Part E page 1789: + * + * C24: Mandatory if the LE Controller supports Connection State and either + * LE Feature (LL Privacy) or LE Feature (Extended Advertising) is supported + */ +#define use_enhanced_conn_complete(dev) (ll_privacy_capable(dev) || \ + ext_adv_capable(dev)) + /* ----- HCI protocols ----- */ #define HCI_PROTO_DEFER 0x01 diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c index 9d8490570b42..9ba2a1a7d481 100644 --- a/net/bluetooth/hci_sync.c +++ b/net/bluetooth/hci_sync.c @@ -3265,10 +3265,10 @@ static int hci_le_set_event_mask_sync(struct hci_dev *hdev) if (hdev->le_features[0] & HCI_LE_DATA_LEN_EXT) events[0] |= 0x40; /* LE Data Length Change */ - /* If the controller supports LL Privacy feature, enable - * the corresponding event. + /* If the controller supports LL Privacy feature or LE Extended Adv, + * enable the corresponding event. */ - if (hdev->le_features[0] & HCI_LE_LL_PRIVACY) + if (use_enhanced_conn_complete(hdev)) events[1] |= 0x02; /* LE Enhanced Connection Complete */ /* If the controller supports Extended Scanner Filter @@ -5188,7 +5188,7 @@ int hci_le_ext_create_conn_sync(struct hci_dev *hdev, struct hci_conn *conn, return __hci_cmd_sync_status_sk(hdev, HCI_OP_LE_EXT_CREATE_CONN, plen, data, HCI_EV_LE_ENHANCED_CONN_COMPLETE, - HCI_CMD_TIMEOUT, NULL); + conn->conn_timeout, NULL); } int hci_le_create_conn_sync(struct hci_dev *hdev, struct hci_conn *conn) @@ -5273,9 +5273,18 @@ int hci_le_create_conn_sync(struct hci_dev *hdev, struct hci_conn *conn) cp.min_ce_len = cpu_to_le16(0x0000); cp.max_ce_len = cpu_to_le16(0x0000); + /* BLUETOOTH CORE SPECIFICATION Version 5.3 | Vol 4, Part E page 2261: + * + * If this event is unmasked and the HCI_LE_Connection_Complete event + * is unmasked, only the HCI_LE_Enhanced_Connection_Complete event is + * sent when a new connection has been created. + */ err = __hci_cmd_sync_status_sk(hdev, HCI_OP_LE_CREATE_CONN, - sizeof(cp), &cp, HCI_EV_LE_CONN_COMPLETE, - HCI_CMD_TIMEOUT, NULL); + sizeof(cp), &cp, + use_enhanced_conn_complete(hdev) ? + HCI_EV_LE_ENHANCED_CONN_COMPLETE : + HCI_EV_LE_CONN_COMPLETE, + conn->conn_timeout, NULL); done: /* Re-enable advertising after the connection attempt is finished. */ -- cgit v1.2.3-70-g09d2 From 008ee9eb8a11bcabf12c91771dd4f470b082bd44 Mon Sep 17 00:00:00 2001 From: Luiz Augusto von Dentz Date: Wed, 2 Mar 2022 13:02:45 -0800 Subject: Bluetooth: hci_sync: Fix not processing all entries on cmd_sync_work hci_cmd_sync_queue can be called multiple times, each adding a hci_cmd_sync_work_entry, before hci_cmd_sync_work is run so this makes sure they are all dequeued properly otherwise it creates a backlog of entries that are never run. Link: https://lore.kernel.org/all/CAJCQCtSeUtHCgsHXLGrSTWKmyjaQDbDNpP4rb0i+RE+L2FTXSA@mail.gmail.com/T/ Fixes: 6a98e3836fa20 ("Bluetooth: Add helper for serialized HCI command execution") Tested-by: Chris Clayton Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Marcel Holtmann --- net/bluetooth/hci_sync.c | 49 +++++++++++++++++++++++------------------------- 1 file changed, 23 insertions(+), 26 deletions(-) (limited to 'net/bluetooth/hci_sync.c') diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c index 9ba2a1a7d481..ab9aa700b6b3 100644 --- a/net/bluetooth/hci_sync.c +++ b/net/bluetooth/hci_sync.c @@ -276,40 +276,37 @@ EXPORT_SYMBOL(__hci_cmd_sync_status); static void hci_cmd_sync_work(struct work_struct *work) { struct hci_dev *hdev = container_of(work, struct hci_dev, cmd_sync_work); - struct hci_cmd_sync_work_entry *entry; - hci_cmd_sync_work_func_t func; - hci_cmd_sync_work_destroy_t destroy; - void *data; bt_dev_dbg(hdev, ""); - mutex_lock(&hdev->cmd_sync_work_lock); - entry = list_first_entry(&hdev->cmd_sync_work_list, - struct hci_cmd_sync_work_entry, list); - if (entry) { - list_del(&entry->list); - func = entry->func; - data = entry->data; - destroy = entry->destroy; - kfree(entry); - } else { - func = NULL; - data = NULL; - destroy = NULL; - } - mutex_unlock(&hdev->cmd_sync_work_lock); + /* Dequeue all entries and run them */ + while (1) { + struct hci_cmd_sync_work_entry *entry; - if (func) { - int err; + mutex_lock(&hdev->cmd_sync_work_lock); + entry = list_first_entry_or_null(&hdev->cmd_sync_work_list, + struct hci_cmd_sync_work_entry, + list); + if (entry) + list_del(&entry->list); + mutex_unlock(&hdev->cmd_sync_work_lock); + + if (!entry) + break; - hci_req_sync_lock(hdev); + bt_dev_dbg(hdev, "entry %p", entry); - err = func(hdev, data); + if (entry->func) { + int err; - if (destroy) - destroy(hdev, data, err); + hci_req_sync_lock(hdev); + err = entry->func(hdev, entry->data); + if (entry->destroy) + entry->destroy(hdev, entry->data, err); + hci_req_sync_unlock(hdev); + } - hci_req_sync_unlock(hdev); + kfree(entry); } } -- cgit v1.2.3-70-g09d2