Bluetooth: fix hci_conn lookup RCU usage + holding refcounts
Subsystems (2)
v3 cover Bluetooth: fix hci_conn lookup RCU usage + holding refcounts
Resending parts of
https://lore.kernel.org/linux-bluetooth/[email protected]/
plus additional hci_conn_params usage fix.
v3
- Copy params->flags in hci_le_pa_create_sync() to reduce number of unlocks in branches.
- Don't convert hci_conn_params to RCU here, as it appears to require sorting out eg. data race vs MGMT_OP_LOAD_CONN_PARAM in field access, and is more complex change than memory safety fix.
To my understanding it would be performance optimization and it's unclear that it is significant: these are on Create LE Connection and Create PA Sync code paths which take hdev->lock in several places eg. in completion callback in any case.
v2:
- Take hdev->lock instead of RCU in hci_update_scan_sync() to guard also the hdev->accept_list access.
- In unpair_device/disconnect_sync, take hdev->lock instead of RCU. This avoids potential access to uninitialized struct device.
In __hci_conn_add() it looks like we should move hci_conn_hash_add(hdev, conn); after hci_conn_init_sysfs(conn); so that the pattern
conn = hci_conn_lookup(...)
if (conn)
hci_conn_get(conn) can be done with RCU without needing hdev->lock. But better done in separate patch series.
Pauli Virtanen (4):
Bluetooth: hci_sync: extend conn_hash lookup critical sections
Bluetooth: mgmt: fix locking in unpair_device/disconnect_sync
Bluetooth: mgmt: hold reference for hci_conn in mgmt_pending_cmds
Bluetooth: hci_sync: hold hdev->lock for hci_conn_params lookups
net/bluetooth/hci_sync.c | 66 +++++++++++++++++++++++++++++++++++----- net/bluetooth/mgmt.c | 42 ++++++++++++++++++++++--- 2 files changed, 97 insertions(+), 11 deletions(-)
Signature · 1 line
2.55.0
PATCH v3 1/4 Bluetooth: hci_sync: extend conn_hash lookup critical sections
Using RCU-protected pointers outside the critical sections without refcount is incorrect and may result to UAF.
Extend critical section to cover both hci_conn_hash lookup and use of the returned conn.
Add surrounding rcu_read_lock() also when return value is not used, in preparation for RCU lockdep requirement to hci_lookup_le_connect().
This avoids concurrent deletion of the conn before we are done dereferencing it.
Also, make sure to hold hdev->lock when accessing hdev->accept_list.
---
Notes:
v3:
- no change
v2:
- take hdev->lock instead of RCU in hci_update_scan_sync() to
guard also the hdev->accept_list accessnet/bluetooth/hci_sync.c | 42 +++++++++++++++++++++++++++++++++++++--- 1 file changed, 39 insertions(+), 3 deletions(-)
net/bluetooth/hci_sync.c +39 -3
@@ -1028,14 +1028,19 @@ static int hci_set_random_addr_sync(struct hci_dev *hdev, bdaddr_t *rpa)* In this kind of scenario skip the update and let the random * address be updated at the next cycle. */ +rcu_read_lock (); +if (bacmp (&hdev->random_addr,BDADDR_ANY ) && (hci_dev_test_flag (hdev,HCI_LE_ADV ) ||hci_lookup_le_connect (hdev))) {bt_dev_dbg (hdev,"Deferring random address update" );hci_dev_set_flag (hdev,HCI_RPA_EXPIRED ); +rcu_read_unlock ();return 0 ; } +rcu_read_unlock (); +return __hci_cmd_sync_status (hdev,HCI_OP_LE_SET_RANDOM_ADDR ,6 , rpa,HCI_CMD_TIMEOUT ); }
@@ -2621,12 +2626,17 @@ static int hci_pause_addr_resolution(struct hci_dev *hdev)/* Cannot disable addr resolution if scanning is enabled or * when initiating an LE connection. */ +rcu_read_lock (); +if (hci_dev_test_flag (hdev,HCI_LE_SCAN ) ||hci_lookup_le_connect (hdev)) { +rcu_read_unlock ();bt_dev_err (hdev,"Command not allowed when scan/LE connect" );return -EPERM ; } +rcu_read_unlock (); +/* Cannot disable addr resolution if advertising is enabled. */ err =hci_pause_advertising_sync (hdev);if (err) {
@@ -2764,6 +2774,8 @@ static u8 hci_update_accept_list_sync(struct hci_dev *hdev)if (hci_dev_test_flag (hdev,HCI_PA_SYNC )) {struct hci_conn *conn; +rcu_read_lock (); + conn =hci_conn_hash_lookup_create_pa_sync (hdev);if (conn) {struct conn_params pa;
@@ -2773,6 +2785,8 @@ static u8 hci_update_accept_list_sync(struct hci_dev *hdev)bacpy (&pa.addr, &conn->dst); pa.addr_type = conn->dst_type; +rcu_read_unlock (); +/* Clear first since there could be addresses left * behind. */
@@ -2782,6 +2796,8 @@ static u8 hci_update_accept_list_sync(struct hci_dev *hdev) err =hci_le_add_accept_list_sync (hdev, &pa, &num_entries); goto done; + }else { +rcu_read_unlock (); } }
@@ -2792,10 +2808,13 @@ static u8 hci_update_accept_list_sync(struct hci_dev *hdev)* the controller. */ list_for_each_entry_safe (b, t, &hdev->le_accept_list, list) { -if (hci_conn_hash_lookup_le (hdev, &b->bdaddr, b->bdaddr_type)) +rcu_read_lock (); + +if (hci_conn_hash_lookup_le (hdev, &b->bdaddr, b->bdaddr_type)) { +rcu_read_unlock ();continue ; + } -/* Pointers not dereferenced, no locks needed */ pend_conn =hci_pend_le_action_lookup (&hdev->pend_le_conns, &b->bdaddr, b->bdaddr_type);
@@ -2803,6 +2822,8 @@ static u8 hci_update_accept_list_sync(struct hci_dev *hdev) &b->bdaddr, b->bdaddr_type); +rcu_read_unlock (); +/* If the device is not likely to connect or report, * remove it from the acceptlist. */
@@ -2929,6 +2950,8 @@ static int hci_le_set_ext_scan_param_sync(struct hci_dev *hdev, u8 type,if (sent) {struct hci_conn *conn; +rcu_read_lock (); + conn =hci_conn_hash_lookup_ba (hdev,PA_LINK , &sent->bdaddr);if (conn) {
@@ -2953,8 +2976,12 @@ static int hci_le_set_ext_scan_param_sync(struct hci_dev *hdev, u8 type, phy++; } +rcu_read_unlock (); +if (num_phy) goto done; + }else { +rcu_read_unlock (); } } }
@@ -3205,12 +3232,16 @@ int hci_update_passive_scan_sync(struct hci_dev *hdev)/* If there is at least one pending LE connection, we should * keep the background scan running. */ +bool exists;/* If controller is connecting, we should not start scanning * since some controllers are not able to scan and connect at * the same time. */ -if (hci_lookup_le_connect (hdev)) +rcu_read_lock (); + exists =hci_lookup_le_connect (hdev); +rcu_read_unlock (); +if (exists)return 0 ;bt_dev_dbg (hdev,"start background scanning" );
@@ -3428,6 +3459,7 @@ int hci_write_fast_connectable_sync(struct hci_dev *hdev, bool enable) }static bool disconnected_accept_list_entries (struct hci_dev *hdev) + __must_hold(&hdev->lock) {struct bdaddr_list *b;
@@ -3468,12 +3500,16 @@ int hci_update_scan_sync(struct hci_dev *hdev)if (hdev->scanning_paused)return 0 ; +hci_dev_lock (hdev); +if (hci_dev_test_flag (hdev,HCI_CONNECTABLE ) ||disconnected_accept_list_entries (hdev)) scan =SCAN_PAGE ;else scan =SCAN_DISABLED ; +hci_dev_unlock (hdev); +if (hci_dev_test_flag (hdev,HCI_DISCOVERABLE )) scan |=SCAN_INQUIRY ;
Signature · 1 line
2.55.0
This is automated email and please do not reply to this email!
Dear submitter,
Thank you for submitting the patches to the linux bluetooth mailing list. This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=1125224
---Test result---
Test Summary:
CheckPatch PASS 2.91 seconds VerifyFixes PASS 0.13 seconds VerifySignedoff PASS 0.14 seconds GitLint FAIL 1.36 seconds SubjectPrefix PASS 0.51 seconds BuildKernel PASS 25.35 seconds CheckAllWarning PASS 28.18 seconds CheckSparse PASS 27.07 seconds BuildKernel32 PASS 24.61 seconds CheckKernelLLVM SKIP 0.00 seconds TestRunnerSetup PASS 461.28 seconds TestRunner_l2cap-tester FAIL 62.18 seconds TestRunner_iso-tester PASS 87.34 seconds TestRunner_bnep-tester PASS 19.46 seconds TestRunner_mgmt-tester FAIL 208.74 seconds TestRunner_rfcomm-tester PASS 25.23 seconds TestRunner_sco-tester PASS 32.15 seconds TestRunner_ioctl-tester PASS 25.37 seconds TestRunner_mesh-tester FAIL 26.07 seconds TestRunner_smp-tester PASS 22.99 seconds TestRunner_userchan-tester PASS 21.93 seconds TestRunner_6lowpan-tester PASS 22.15 seconds IncrementalBuild PASS 39.87 seconds
Details
##############################
Test: GitLint - FAIL
Desc: Run gitlint
Output:
[v3,2/4] Bluetooth: mgmt: fix locking in unpair_device/disconnect_sync
18: B2 Line has trailing whitespace: " "
##############################
Test: CheckKernelLLVM - SKIP
Desc: Build kernel with LLVM + context analysis Output:
Clang not found
##############################
Test: TestRunner_l2cap-tester - FAIL
Desc: Run l2cap-tester with test-runner Output:
Total: 96, Passed: 95 (99.0%), Failed: 1, Not Run: 0
Failed Test Cases
L2CAP BR/EDR Server - Set PHY 1M Failed 0.287 seconds
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner Output:
Total: 494, Passed: 489 (99.0%), Failed: 1, Not Run: 4
Failed Test Cases
Read Exp Feature - Success Failed 0.234 seconds
##############################
Test: TestRunner_mesh-tester - FAIL
Desc: Run mesh-tester with test-runner Output:
Total: 10, Passed: 8 (80.0%), Failed: 2, Not Run: 0
Failed Test Cases
Mesh - Send cancel - 1 Timed out 2.786 seconds Mesh - Send cancel - 2 Timed out 1.990 seconds
https://github.com/bluez/bluetooth-next/pull/420
---
Regards,
Linux Bluetooth
PATCH v3 2/4 Bluetooth: mgmt: fix locking in unpair_device/disconnect_sync
In reply to Pauli VirtanenDereferencing RCU-protected pointers outside critical sections is invalid and may lead to UAF.
Take hdev->lock for hci_conn lookup and hci_abort_conn(). Don't use RCU to ensure the conn is fully initialized at this point.
---
Notes:
v3:
- no change
v2:
- take hdev->lock instead of RCU, to make sure the conn object is fully initialized before hci_conn_abort_sync()
hci_conn_abort_sync() may not be called with hdev->lock held when called from hci_sync workqueue.
net/bluetooth/mgmt.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
net/bluetooth/mgmt.c +16 -0
@@ -3091,6 +3091,8 @@ static int unpair_device_sync(struct hci_dev *hdev, void *data)struct mgmt_cp_unpair_device *cp = cmd->param;struct hci_conn *conn; +hci_dev_lock (hdev); +if (cp->addr.type ==BDADDR_BREDR ) conn =hci_conn_hash_lookup_ba (hdev,ACL_LINK , &cp->addr.bdaddr);
@@ -3098,6 +3100,11 @@ static int unpair_device_sync(struct hci_dev *hdev, void *data) conn =hci_conn_hash_lookup_le (hdev, &cp->addr.bdaddr,le_addr_type (cp->addr.type)); +if (conn) +hci_conn_get (conn); + +hci_dev_unlock (hdev); +if (!conn)return 0 ;
@@ -3105,6 +3112,7 @@ static int unpair_device_sync(struct hci_dev *hdev, void *data)* will clean up the connection no matter the error. */ hci_abort_conn (conn,HCI_ERROR_REMOTE_USER_TERM ); +hci_conn_put (conn);return 0 ; }
@@ -3252,6 +3260,8 @@ static int disconnect_sync(struct hci_dev *hdev, void *data)struct mgmt_cp_disconnect *cp = cmd->param;struct hci_conn *conn; +hci_dev_lock (hdev); +if (cp->addr.type ==BDADDR_BREDR ) conn =hci_conn_hash_lookup_ba (hdev,ACL_LINK , &cp->addr.bdaddr);
@@ -3259,6 +3269,11 @@ static int disconnect_sync(struct hci_dev *hdev, void *data) conn =hci_conn_hash_lookup_le (hdev, &cp->addr.bdaddr,le_addr_type (cp->addr.type)); +if (conn) +hci_conn_get (conn); + +hci_dev_unlock (hdev); +if (!conn)return -ENOTCONN ;
@@ -3266,6 +3281,7 @@ static int disconnect_sync(struct hci_dev *hdev, void *data)* will clean up the connection no matter the error. */ hci_abort_conn (conn,HCI_ERROR_REMOTE_USER_TERM ); +hci_conn_put (conn);return 0 ; }
Signature · 1 line
2.55.0
PATCH v3 3/4 Bluetooth: mgmt: hold reference for hci_conn in mgmt_pending_cmds
In reply to Pauli VirtanenDereferencing RCU-protected pointers outside critical sections is invalid and may lead to UAF. Use of hci_conn in hci_sync callbacks also needs to hold refcount to avoid UAF.
Take appropriate locks for hci_conn lookups, and take refcount for hci_conn pointers stored in mgmt_pending_cmd so that the pointer stays valid.
When accessing conn->state, ensure hdev->lock is held to avoid data race.
---
Notes:
v3:
- no change
v2:
- no change
net/bluetooth/mgmt.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-)
net/bluetooth/mgmt.c +22 -4
@@ -7404,6 +7404,9 @@ static void get_conn_info_complete(struct hci_dev *hdev, void *data, int err) rp.max_tx_power =HCI_TX_POWER_INVALID ; } +if (conn) +hci_conn_put (conn); +mgmt_cmd_complete (cmd->sk, cmd->hdev->id,MGMT_OP_GET_CONN_INFO , status, &rp,sizeof (rp));
@@ -7418,6 +7421,8 @@ static int get_conn_info_sync(struct hci_dev *hdev, void *data)int err;__le16 handle; +hci_dev_lock (hdev); +/* Make sure we are still connected */ if (cp->addr.type ==BDADDR_BREDR ) conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK,
@@ -7425,12 +7430,16 @@ static int get_conn_info_sync(struct hci_dev *hdev, void *data)else conn =hci_conn_hash_lookup_ba (hdev,LE_LINK , &cp->addr.bdaddr); -if (!conn || conn->state !=BT_CONNECTED ) +if (!conn || conn->state !=BT_CONNECTED ) { +hci_dev_unlock (hdev);return MGMT_STATUS_NOT_CONNECTED ; + } - cmd->user_data = conn; + cmd->user_data =hci_conn_get (conn); handle =cpu_to_le16 (conn->handle); +hci_dev_unlock (hdev); +/* Refresh RSSI each time */ err =hci_read_rssi_sync (hdev, handle);
@@ -7564,6 +7573,9 @@ static void get_clock_info_complete(struct hci_dev *hdev, void *data, int err) } complete: +if (conn) +hci_conn_put (conn); +mgmt_cmd_complete (cmd->sk, cmd->hdev->id, cmd->opcode, status, &rp,sizeof (rp));
@@ -7580,15 +7592,21 @@ static int get_clock_info_sync(struct hci_dev *hdev, void *data)memset (&hci_cp,0 ,sizeof (hci_cp));hci_read_clock_sync (hdev, &hci_cp); +hci_dev_lock (hdev); +/* Make sure connection still exists */ conn =hci_conn_hash_lookup_ba (hdev,ACL_LINK , &cp->addr.bdaddr); -if (!conn || conn->state !=BT_CONNECTED ) +if (!conn || conn->state !=BT_CONNECTED ) { +hci_dev_unlock (hdev);return MGMT_STATUS_NOT_CONNECTED ; + } - cmd->user_data = conn; + cmd->user_data =hci_conn_get (conn); hci_cp.handle =cpu_to_le16 (conn->handle); hci_cp.which =0x01 ;/* Piconet clock */ +hci_dev_unlock (hdev); +return hci_read_clock_sync (hdev, &hci_cp); }
Signature · 1 line
2.55.0
PATCH v3 4/4 Bluetooth: hci_sync: hold hdev->lock for hci_conn_params lookups
In reply to Pauli Virtanenhci_conn_params_lookup requires hdev->lock be held, otherwise the list iteration or param access is not safe.
Hold hdev->lock for params lookups in hci_sync.
---
Notes:
v3:
- copy params->flags in hci_le_pa_create_sync() to reduce number of unlocks in branches. Note the lock also protects the le hci_conn.
v2:
- no change
net/bluetooth/hci_sync.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)
net/bluetooth/hci_sync.c +20 -4
@@ -6677,6 +6677,8 @@ static int hci_le_create_conn_sync(struct hci_dev *hdev, void *data)if (!hci_dev_test_flag (hdev,HCI_LE_SIMULTANEOUS_ROLES ))hci_pause_advertising_sync (hdev); +hci_dev_lock (hdev); + params =hci_conn_params_lookup (hdev, &conn->dst, conn->dst_type);if (params) { conn->le_conn_min_interval = params->conn_min_interval;
@@ -6690,6 +6692,8 @@ static int hci_le_create_conn_sync(struct hci_dev *hdev, void *data) conn->le_supv_timeout = hdev->le_supv_timeout; } +hci_dev_unlock (hdev); +/* If controller is scanning, we stop it since some controllers are * not able to scan and connect at the same time. Also set the * HCI_LE_SCAN_INTERRUPTED flag so that the command complete
@@ -7247,13 +7251,13 @@ static void create_pa_complete(struct hci_dev *hdev, void *data, int err) }static int hci_le_past_params_sync (struct hci_dev *hdev,struct hci_conn *conn, -struct hci_conn *acl,struct bt_iso_qos *qos) +u16 acl_handle,struct bt_iso_qos *qos) {struct hci_cp_le_past_params cp;int err;memset (&cp,0 ,sizeof (cp)); - cp.handle =cpu_to_le16 (acl->handle); + cp.handle =cpu_to_le16 (acl_handle);/* An HCI_LE_Periodic_Advertising_Sync_Transfer_Received event is sent * to the Host. HCI_LE_Periodic_Advertising_Report events will be * enabled with duplicate filtering enabled.
@@ -7318,16 +7322,28 @@ static int hci_le_pa_create_sync(struct hci_dev *hdev, void *data)* 2. Check if that HCI_CONN_FLAG_PAST has been set which indicates that * user really intended to use PAST. */ +hci_dev_lock (hdev); + le =hci_conn_hash_lookup_le (hdev, &conn->dst, conn->dst_type);if (le) {struct hci_conn_params *params; +hci_conn_flags_t flags =0 ; +u16 le_handle = le->handle; params =hci_conn_params_lookup (hdev, &le->dst, le->dst_type); -if (params && params->flags &HCI_CONN_FLAG_PAST ) { - err =hci_le_past_params_sync (hdev, conn, le, qos); +if (params) + flags = params->flags; + +hci_dev_unlock (hdev); + +if (flags &HCI_CONN_FLAG_PAST ) { + err =hci_le_past_params_sync (hdev, conn, le_handle, + qos);if (!err) goto done; } + }else { +hci_dev_unlock (hdev); }/* SID has not been set listen for HCI_EV_LE_EXT_ADV_REPORT to update
Signature · 1 line
2.55.0
This series was applied to bluetooth/bluetooth-next.git (master) by Luiz Augusto von Dentz <[email protected]>:
Hello:
This series was applied to bluetooth/bluetooth-next.git (master) by Luiz Augusto von Dentz <[email protected]>:
Quoted 9 lines · On Fri, 10 Jul 2026 11:23:39 +0300 you wrote:
Resending parts of
https://lore.kernel.org/linux-bluetooth/[email protected]/
plus additionalhci_conn_paramsusage fix.v3
- Copyparams->flagsinhci_le_pa_create_sync()to reduce number of unlocks in branches.[...]
Here is the summary with links:
- [v3,1/4] Bluetooth: hci_sync: extend conn_hash lookup critical sections
https://git.kernel.org/bluetooth/bluetooth-next/c/17f5bfb02164 - [v3,2/4] Bluetooth: mgmt: fix locking in unpair_device/disconnect_sync https://git.kernel.org/bluetooth/bluetooth-next/c/f3f75fd597f2 - [v3,3/4] Bluetooth: mgmt: hold reference for hci_conn in mgmt_pending_cmds https://git.kernel.org/bluetooth/bluetooth-next/c/137501e0242f - [v3,4/4] Bluetooth: hci_sync: hold hdev->lock for hci_conn_params lookups https://git.kernel.org/bluetooth/bluetooth-next/c/b755b4141c64
You are awesome, thank you!
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