hci_update_accept_list_sync iterates over hdev->pend_le_conns and
hdev->pend_le_reports, and waits for controller events in the loop body,
without holding hdev lock.
Meanwhile, these lists and the items may be modified e.g. by
le_scan_cleanup. This can invalidate the list cursor in the ongoing
iterations, resulting to invalid behavior (eg use-after-free).
Use RCU for the hci_conn_params action lists. Since the loop bodies in
hci_sync block and we cannot use RCU for the whole loop, add
hci_conn_params.add_pending to keep track which items are left. Copy
data to avoid needing lock on hci_conn_params. Only the flags field is
written from elsewhere, so READ_ONCE/WRITE_ONCE should guarantee we read
valid values.
Free params everywhere with hci_conn_params_free so the cleanup is
guaranteed to be done properly.
This fixes the following, which can be triggered at least by changing
hci_le_set_cig_params to always return false, and running BlueZ
iso-tester, which causes connections to be created and dropped fast:
==================================================================
BUG: KASAN: slab-use-after-free in hci_update_passive_scan_sync (net/bluetooth/hci_sync.c:2536 net/bluetooth/hci_sync.c:2723 net/bluetooth/hci_sync.c:2841)
Read of size 8 at addr ffff888001265018 by task kworker/u3:0/32
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014
Workqueue: hci0 hci_cmd_sync_work
Call Trace:
<TASK>
dump_stack_lvl (./arch/x86/include/asm/irqflags.h:134 lib/dump_stack.c:107)
print_report (mm/kasan/report.c:320 mm/kasan/report.c:430)
? __virt_addr_valid (./include/linux/mmzone.h:1915 ./include/linux/mmzone.h:2011 arch/x86/mm/physaddr.c:65)
? hci_update_passive_scan_sync (net/bluetooth/hci_sync.c:2536 net/bluetooth/hci_sync.c:2723 net/bluetooth/hci_sync.c:2841)
kasan_report (mm/kasan/report.c:538)
? hci_update_passive_scan_sync (net/bluetooth/hci_sync.c:2536 net/bluetooth/hci_sync.c:2723 net/bluetooth/hci_sync.c:2841)
hci_update_passive_scan_sync (net/bluetooth/hci_sync.c:2536 net/bluetooth/hci_sync.c:2723 net/bluetooth/hci_sync.c:2841)
? __pfx_hci_update_passive_scan_sync (net/bluetooth/hci_sync.c:2780)
? mutex_lock (kernel/locking/mutex.c:282)
? __pfx_mutex_lock (kernel/locking/mutex.c:282)
? __pfx_mutex_unlock (kernel/locking/mutex.c:538)
? __pfx_update_passive_scan_sync (net/bluetooth/hci_sync.c:2861)
hci_cmd_sync_work (net/bluetooth/hci_sync.c:306)
process_one_work (./arch/x86/include/asm/preempt.h:27 kernel/workqueue.c:2399)
worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2538)
? __pfx_worker_thread (kernel/workqueue.c:2480)
kthread (kernel/kthread.c:376)
? __pfx_kthread (kernel/kthread.c:331)
ret_from_fork (arch/x86/entry/entry_64.S:314)
</TASK>
Allocated by task 31:
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_params_add (./include/linux/slab.h:580 ./include/linux/slab.h:720 net/bluetooth/hci_core.c:2277)
hci_connect_le_scan (net/bluetooth/hci_conn.c:1419 net/bluetooth/hci_conn.c:1589)
hci_connect_cis (net/bluetooth/hci_conn.c:2266)
iso_connect_cis (net/bluetooth/iso.c:390)
iso_sock_connect (net/bluetooth/iso.c:899)
__sys_connect (net/socket.c:2003 net/socket.c:2020)
__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 15:
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:3787 mm/slub.c:3800)
hci_conn_params_del (net/bluetooth/hci_core.c:2323)
le_scan_cleanup (net/bluetooth/hci_conn.c:202)
process_one_work (./arch/x86/include/asm/preempt.h:27 kernel/workqueue.c:2399)
worker_thread (./include/linux/list.h:292 kernel/workqueue.c:2538)
kthread (kernel/kthread.c:376)
ret_from_fork (arch/x86/entry/entry_64.S:314)
==================================================================
Fixes: e8907f76544f ("Bluetooth: hci_sync: Make use of hci_cmd_sync_queue set 3")
Signed-off-by: Pauli Virtanen <pav@xxxxxx>
---
Notes:
v2: use RCU
include/net/bluetooth/hci_core.h | 5 ++
net/bluetooth/hci_conn.c | 9 ++--
net/bluetooth/hci_core.c | 34 +++++++++---
net/bluetooth/hci_event.c | 12 ++---
net/bluetooth/hci_sync.c | 93 ++++++++++++++++++++++++++++----
net/bluetooth/mgmt.c | 30 +++++------
6 files changed, 141 insertions(+), 42 deletions(-)
diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index 683666ea210c..8c6ac6d29c62 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -822,6 +822,8 @@ struct hci_conn_params {
struct hci_conn *conn;
bool explicit_connect;
+ /* Accessed without hdev->lock: */
+ bool add_pending;
hci_conn_flags_t flags;
u8 privacy_mode;
};
@@ -1605,6 +1607,9 @@ struct hci_conn_params *hci_conn_params_add(struct hci_dev *hdev,
bdaddr_t *addr, u8 addr_type);
void hci_conn_params_del(struct hci_dev *hdev, bdaddr_t *addr, u8 addr_type);
void hci_conn_params_clear_disabled(struct hci_dev *hdev);
+void hci_conn_params_free(struct hci_conn_params *param);
+void hci_conn_params_set_pending(struct hci_conn_params *param,
+ struct list_head *list);
struct hci_conn_params *hci_pend_le_action_lookup(struct list_head *list,
bdaddr_t *addr,
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 7d4941e6dbdf..ae9a35d1405b 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -118,7 +118,7 @@ static void hci_connect_le_scan_cleanup(struct hci_conn *conn, u8 status)
*/
params->explicit_connect = false;
- list_del_init(¶ms->action);
+ hci_conn_params_set_pending(params, NULL);
switch (params->auto_connect) {
case HCI_AUTO_CONN_EXPLICIT:
@@ -127,10 +127,10 @@ static void hci_connect_le_scan_cleanup(struct hci_conn *conn, u8 status)
return;
case HCI_AUTO_CONN_DIRECT:
case HCI_AUTO_CONN_ALWAYS:
- list_add(¶ms->action, &hdev->pend_le_conns);
+ hci_conn_params_set_pending(params, &hdev->pend_le_conns);
break;
case HCI_AUTO_CONN_REPORT:
- list_add(¶ms->action, &hdev->pend_le_reports);
+ hci_conn_params_set_pending(params, &hdev->pend_le_reports);
break;
default:
break;
@@ -1435,8 +1435,7 @@ static int hci_explicit_conn_params_set(struct hci_dev *hdev,
if (params->auto_connect == HCI_AUTO_CONN_DISABLED ||
params->auto_connect == HCI_AUTO_CONN_REPORT ||
params->auto_connect == HCI_AUTO_CONN_EXPLICIT) {
- list_del_init(¶ms->action);
- list_add(¶ms->action, &hdev->pend_le_conns);
+ hci_conn_params_set_pending(params, &hdev->pend_le_conns);
}
params->explicit_connect = true;
diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index 48917c68358d..7992a61fe1fd 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -2249,21 +2249,41 @@ struct hci_conn_params *hci_conn_params_lookup(struct hci_dev *hdev,
return NULL;
}
-/* This function requires the caller holds hdev->lock */
+/* This function requires the caller holds hdev->lock or rcu_read_lock */
struct hci_conn_params *hci_pend_le_action_lookup(struct list_head *list,
bdaddr_t *addr, u8 addr_type)
{
struct hci_conn_params *param;
- list_for_each_entry(param, list, action) {
+ rcu_read_lock();
+
+ list_for_each_entry_rcu(param, list, action) {
if (bacmp(¶m->addr, addr) == 0 &&
- param->addr_type == addr_type)
+ param->addr_type == addr_type) {
+ rcu_read_unlock();
return param;
+ }
}
+ rcu_read_unlock();
+
return NULL;
}
+/* This function requires the caller holds hdev->lock */
+void hci_conn_params_set_pending(struct hci_conn_params *param,
+ struct list_head *list)
+{
+ if (!list_empty(¶m->action)) {
+ list_del_rcu(¶m->action);
+ synchronize_rcu();
+ INIT_LIST_HEAD(¶m->action);
+ }
+
+ if (list)
+ list_add_rcu(¶m->action, list);
+}
+
/* This function requires the caller holds hdev->lock */
struct hci_conn_params *hci_conn_params_add(struct hci_dev *hdev,
bdaddr_t *addr, u8 addr_type)
@@ -2297,14 +2317,15 @@ struct hci_conn_params *hci_conn_params_add(struct hci_dev *hdev,
return params;
}
-static void hci_conn_params_free(struct hci_conn_params *params)
+void hci_conn_params_free(struct hci_conn_params *params)
{
+ hci_conn_params_set_pending(params, NULL);
+
if (params->conn) {
hci_conn_drop(params->conn);
hci_conn_put(params->conn);
}
- list_del(¶ms->action);
list_del(¶ms->list);
kfree(params);
}
@@ -2342,8 +2363,7 @@ void hci_conn_params_clear_disabled(struct hci_dev *hdev)
continue;
}
- list_del(¶ms->list);
- kfree(params);
+ hci_conn_params_free(params);
}
BT_DBG("All LE disabled connection parameters were removed");
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 7c199f7361f7..8187c9f827fa 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -1564,7 +1564,7 @@ static u8 hci_cc_le_set_privacy_mode(struct hci_dev *hdev, void *data,
params = hci_conn_params_lookup(hdev, &cp->bdaddr, cp->bdaddr_type);
if (params)
- params->privacy_mode = cp->mode;
+ WRITE_ONCE(params->privacy_mode, cp->mode);
hci_dev_unlock(hdev);
@@ -2804,8 +2804,8 @@ static void hci_cs_disconnect(struct hci_dev *hdev, u8 status)
case HCI_AUTO_CONN_DIRECT:
case HCI_AUTO_CONN_ALWAYS:
- list_del_init(¶ms->action);
- list_add(¶ms->action, &hdev->pend_le_conns);
+ hci_conn_params_set_pending(params,
+ &hdev->pend_le_conns);
break;
default:
@@ -3423,8 +3423,8 @@ static void hci_disconn_complete_evt(struct hci_dev *hdev, void *data,
case HCI_AUTO_CONN_DIRECT:
case HCI_AUTO_CONN_ALWAYS:
- list_del_init(¶ms->action);
- list_add(¶ms->action, &hdev->pend_le_conns);
+ hci_conn_params_set_pending(params,
+ &hdev->pend_le_conns);
hci_update_passive_scan(hdev);
break;
@@ -5972,7 +5972,7 @@ static void le_conn_complete_evt(struct hci_dev *hdev, u8 status,
params = hci_pend_le_action_lookup(&hdev->pend_le_conns, &conn->dst,
conn->dst_type);
if (params) {
- list_del_init(¶ms->action);
+ hci_conn_params_set_pending(params, NULL);
if (params->conn) {
hci_conn_drop(params->conn);
hci_conn_put(params->conn);
diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 97da5bcaa904..da12e286ee64 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -2160,15 +2160,23 @@ static int hci_le_del_accept_list_sync(struct hci_dev *hdev,
return 0;
}
+struct conn_params {
+ bdaddr_t addr;
+ u8 addr_type;
+ hci_conn_flags_t flags;
+ u8 privacy_mode;
+};
+
/* Adds connection to resolve list if needed.
* Setting params to NULL programs local hdev->irk
*/
static int hci_le_add_resolve_list_sync(struct hci_dev *hdev,
- struct hci_conn_params *params)
+ struct conn_params *params)
{
struct hci_cp_le_add_to_resolv_list cp;
struct smp_irk *irk;
struct bdaddr_list_with_irk *entry;
+ struct hci_conn_params *p;
if (!use_ll_privacy(hdev))
return 0;
@@ -2203,6 +2211,16 @@ static int hci_le_add_resolve_list_sync(struct hci_dev *hdev,
/* Default privacy mode is always Network */
params->privacy_mode = HCI_NETWORK_PRIVACY;
+ rcu_read_lock();
+ p = hci_pend_le_action_lookup(&hdev->pend_le_conns,
+ ¶ms->addr, params->addr_type);
+ if (!p)
+ p = hci_pend_le_action_lookup(&hdev->pend_le_reports,
+ ¶ms->addr, params->addr_type);
+ if (p)
+ WRITE_ONCE(p->privacy_mode, HCI_NETWORK_PRIVACY);
+ rcu_read_unlock();
+
done:
if (hci_dev_test_flag(hdev, HCI_PRIVACY))
memcpy(cp.local_irk, hdev->irk, 16);
@@ -2215,7 +2233,7 @@ static int hci_le_add_resolve_list_sync(struct hci_dev *hdev,
/* Set Device Privacy Mode. */
static int hci_le_set_privacy_mode_sync(struct hci_dev *hdev,
- struct hci_conn_params *params)
+ struct conn_params *params)
{
struct hci_cp_le_set_privacy_mode cp;
struct smp_irk *irk;
@@ -2240,6 +2258,8 @@ static int hci_le_set_privacy_mode_sync(struct hci_dev *hdev,
bacpy(&cp.bdaddr, &irk->bdaddr);
cp.mode = HCI_DEVICE_PRIVACY;
+ /* Note: params->privacy_mode is not updated since it is a copy */
+
return __hci_cmd_sync_status(hdev, HCI_OP_LE_SET_PRIVACY_MODE,
sizeof(cp), &cp, HCI_CMD_TIMEOUT);
}
@@ -2249,7 +2269,7 @@ static int hci_le_set_privacy_mode_sync(struct hci_dev *hdev,
* properly set the privacy mode.
*/
static int hci_le_add_accept_list_sync(struct hci_dev *hdev,
- struct hci_conn_params *params,
+ struct conn_params *params,
u8 *num_entries)
{
struct hci_cp_le_add_to_accept_list cp;
@@ -2447,6 +2467,51 @@ struct sk_buff *hci_read_local_oob_data_sync(struct hci_dev *hdev,
return __hci_cmd_sync_sk(hdev, opcode, 0, NULL, 0, HCI_CMD_TIMEOUT, sk);
}
+static void conn_params_add_iter_init(struct list_head *list)
+{
+ struct hci_conn_params *params;
+
+ rcu_read_lock();
+
+ list_for_each_entry_rcu(params, list, action)
+ params->add_pending = true;
+
+ rcu_read_unlock();
+}
+
+static bool conn_params_add_iter_next(struct list_head *list,
+ struct conn_params *item)
+{
+ struct hci_conn_params *params;
+
+ rcu_read_lock();
+
+ list_for_each_entry_rcu(params, list, action) {
+ if (!params->add_pending)
+ continue;
+
+ /* No hdev->lock, but: addr, addr_type are immutable.
+ * privacy_mode is only written by us or in
+ * hci_cc_le_set_privacy_mode that we wait for.
+ * We should be idempotent so MGMT updating flags
+ * while we are processing is OK.
+ */
+ bacpy(&item->addr, ¶ms->addr);
+ item->addr_type = params->addr_type;
+ item->flags = READ_ONCE(params->flags);
+ item->privacy_mode = READ_ONCE(params->privacy_mode);
+
+ params->add_pending = false;
+
+ rcu_read_unlock();
+ return true;
+ }
+
+ rcu_read_unlock();
+
+ return false;
+}
+
/* Device must not be scanning when updating the accept list.
*
* Update is done using the following sequence:
@@ -2466,7 +2531,7 @@ struct sk_buff *hci_read_local_oob_data_sync(struct hci_dev *hdev,
*/
static u8 hci_update_accept_list_sync(struct hci_dev *hdev)
{
- struct hci_conn_params *params;
+ struct conn_params params;
struct bdaddr_list *b, *t;
u8 num_entries = 0;
bool pend_conn, pend_report;
@@ -2504,6 +2569,7 @@ static u8 hci_update_accept_list_sync(struct hci_dev *hdev)
if (hci_conn_hash_lookup_le(hdev, &b->bdaddr, b->bdaddr_type))
continue;
+ /* Pointers not dereferenced, no locks needed */
pend_conn = hci_pend_le_action_lookup(&hdev->pend_le_conns,
&b->bdaddr,
b->bdaddr_type);
@@ -2532,9 +2598,15 @@ static u8 hci_update_accept_list_sync(struct hci_dev *hdev)
* available accept list entries in the controller, then
* just abort and return filer policy value to not use the
* accept list.
+ *
+ * The list and params may be mutated while we wait for events,
+ * so use special iteration with copies.
*/
- list_for_each_entry(params, &hdev->pend_le_conns, action) {
- err = hci_le_add_accept_list_sync(hdev, params, &num_entries);
+
+ conn_params_add_iter_init(&hdev->pend_le_conns);
+
+ while (conn_params_add_iter_next(&hdev->pend_le_conns, ¶ms)) {
+ err = hci_le_add_accept_list_sync(hdev, ¶ms, &num_entries);
if (err)
goto done;
}
@@ -2543,8 +2615,11 @@ static u8 hci_update_accept_list_sync(struct hci_dev *hdev)
* the list of pending reports and also add these to the
* accept list if there is still space. Abort if space runs out.
*/
- list_for_each_entry(params, &hdev->pend_le_reports, action) {
- err = hci_le_add_accept_list_sync(hdev, params, &num_entries);
+
+ conn_params_add_iter_init(&hdev->pend_le_reports);
+
+ while (conn_params_add_iter_next(&hdev->pend_le_reports, ¶ms)) {
+ err = hci_le_add_accept_list_sync(hdev, ¶ms, &num_entries);
if (err)
goto done;
}
@@ -4837,12 +4912,12 @@ static void hci_pend_le_actions_clear(struct hci_dev *hdev)
struct hci_conn_params *p;
list_for_each_entry(p, &hdev->le_conn_params, list) {
+ hci_conn_params_set_pending(p, NULL);
if (p->conn) {
hci_conn_drop(p->conn);
hci_conn_put(p->conn);
p->conn = NULL;
}
- list_del_init(&p->action);
}
BT_DBG("All LE pending actions cleared");
diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index 61c8e1b8f3b0..b35b1c685b86 100644
--- a/net/bluetooth/mgmt.c
+++ b/net/bluetooth/mgmt.c
@@ -1303,15 +1303,15 @@ static void restart_le_actions(struct hci_dev *hdev)
/* Needed for AUTO_OFF case where might not "really"
* have been powered off.
*/
- list_del_init(&p->action);
+ hci_conn_params_set_pending(p, NULL);
switch (p->auto_connect) {
case HCI_AUTO_CONN_DIRECT:
case HCI_AUTO_CONN_ALWAYS:
- list_add(&p->action, &hdev->pend_le_conns);
+ hci_conn_params_set_pending(p, &hdev->pend_le_conns);
break;
case HCI_AUTO_CONN_REPORT:
- list_add(&p->action, &hdev->pend_le_reports);
+ hci_conn_params_set_pending(p, &hdev->pend_le_reports);
break;
default:
break;
@@ -5175,7 +5175,7 @@ static int set_device_flags(struct sock *sk, struct hci_dev *hdev, void *data,
goto unlock;
}
- params->flags = current_flags;
+ WRITE_ONCE(params->flags, current_flags);
status = MGMT_STATUS_SUCCESS;
/* Update passive scan if HCI_CONN_FLAG_DEVICE_PRIVACY
@@ -7586,7 +7586,7 @@ static int hci_conn_params_set(struct hci_dev *hdev, bdaddr_t *addr,
if (params->auto_connect == auto_connect)
return 0;
- list_del_init(¶ms->action);
+ hci_conn_params_set_pending(params, NULL);
switch (auto_connect) {
case HCI_AUTO_CONN_DISABLED:
@@ -7595,18 +7595,22 @@ static int hci_conn_params_set(struct hci_dev *hdev, bdaddr_t *addr,
* connect to device, keep connecting.
*/
if (params->explicit_connect)
- list_add(¶ms->action, &hdev->pend_le_conns);
+ hci_conn_params_set_pending(params,
+ &hdev->pend_le_conns);
break;
case HCI_AUTO_CONN_REPORT:
if (params->explicit_connect)
- list_add(¶ms->action, &hdev->pend_le_conns);
+ hci_conn_params_set_pending(params,
+ &hdev->pend_le_conns);
else
- list_add(¶ms->action, &hdev->pend_le_reports);
+ hci_conn_params_set_pending(params,
+ &hdev->pend_le_reports);
break;
case HCI_AUTO_CONN_DIRECT:
case HCI_AUTO_CONN_ALWAYS:
if (!is_connected(hdev, addr, addr_type))
- list_add(¶ms->action, &hdev->pend_le_conns);
+ hci_conn_params_set_pending(params,
+ &hdev->pend_le_conns);
break;
}
@@ -7829,9 +7833,7 @@ static int remove_device(struct sock *sk, struct hci_dev *hdev,
goto unlock;
}
- list_del(¶ms->action);
- list_del(¶ms->list);
- kfree(params);
+ hci_conn_params_free(params);
device_removed(sk, hdev, &cp->addr.bdaddr, cp->addr.type);
} else {
@@ -7862,9 +7864,7 @@ static int remove_device(struct sock *sk, struct hci_dev *hdev,
p->auto_connect = HCI_AUTO_CONN_EXPLICIT;
continue;
}
- list_del(&p->action);
- list_del(&p->list);
- kfree(p);
+ hci_conn_params_free(p);
}
bt_dev_dbg(hdev, "All LE connection parameters were removed");
--
2.40.1
