[PATCH v5 0/7] Bluetooth: hci_conn: hold conn references in hci_sync tasks

[PATCH v5 0/7] Bluetooth: hci_conn: hold conn references in hci_sync tasks

[Pauli Virtanen]

Have hci_sync tasks hold reference to hci_conn pointer they want to use
later.

Avoids UAFs and passing potentially reused (possible even if very
unlikely) pointers to hci_conn_valid().

hci_conn_del() dequeues running works for the same connection, but this
has no effect if the work is already started running, which is the race
condition here.

v5:
- resend
- no need to check hci_conn_valid() in create_big_complete, the bit is
  safe to clear also if hci_conn_del() has run

v4:
- Check !conn in hci_connect_big_sync() first.
  It's probably bug in iso.c that it may call this with NULL, but
  probably better fixed separately.

v3:
- resending some rebased parts from
  https://lore.kernel.org/linux-bluetooth/cover.1762100290.git.pav@iki.fi/
  https://lore.kernel.org/linux-bluetooth/cover.1758481869.git.pav@iki.fi/

Pauli Virtanen (7):
  Bluetooth: hci_conn: hold conn reference in abort_conn_sync()
  Bluetooth: hci_sync: hold conn in hci_connect_acl/le_sync() callbacks
  Bluetooth: hci_sync: hold conn in hci_connect_big_sync() callback
  Bluetooth: hci_sync: hold conn in hci_connect_pa_sync() callback
  Bluetooth: hci_sync: hold conn in hci_past_sync() callback
  Bluetooth: hci_sync: fix hci_conn_del() use in hci_le_create_conn_sync
  Bluetooth: hci_sync: remove unnecessary hci_conn_get in
    create_conn_sync

 net/bluetooth/hci_conn.c | 12 +++++-
 net/bluetooth/hci_sync.c | 85 +++++++++++++++++++++++++---------------
 2 files changed, 65 insertions(+), 32 deletions(-)

-- 
2.55.0

[PATCH v5 1/7] Bluetooth: hci_conn: hold conn reference in abort_conn_sync()

[Pauli Virtanen]

There is theoretical UAF if the conn is freed while the hci_sync task is
running.

Hold refcount to avoid that.

Fixes: 227a0cdf4a02 ("Bluetooth: MGMT: Fix not generating command complete for MGMT_OP_DISCONNECT")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
---

Notes:
    v5:
    - no change
    v4:
    - no change
    v3:
    - split to multiple patches per different Fixes:

 net/bluetooth/hci_conn.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 1966cd153d97..6036ff66d8d9 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -3163,6 +3163,13 @@ static int abort_conn_sync(struct hci_dev *hdev, void *data)
 	return hci_abort_conn_sync(hdev, conn, conn->abort_reason);
 }
 
+static void abort_conn_destroy(struct hci_dev *hdev, void *data, int err)
+{
+	struct hci_conn *conn = data;
+
+	hci_conn_put(conn);
+}
+
 int hci_abort_conn(struct hci_conn *conn, u8 reason)
 {
 	struct hci_dev *hdev = conn->hdev;
@@ -3188,7 +3195,10 @@ int hci_abort_conn(struct hci_conn *conn, u8 reason)
 	 * as a result to MGMT_OP_DISCONNECT/MGMT_OP_UNPAIR which does
 	 * already queue its callback on cmd_sync_work.
 	 */
-	err = hci_cmd_sync_run_once(hdev, abort_conn_sync, conn, NULL);
+	err = hci_cmd_sync_run_once(hdev, abort_conn_sync, hci_conn_get(conn),
+				    abort_conn_destroy);
+	if (err)
+		hci_conn_put(conn);
 	return (err == -EEXIST) ? 0 : err;
 }
 
-- 
2.55.0

[PATCH v5 2/7] Bluetooth: hci_sync: hold conn in hci_connect_acl/le_sync() callbacks

[Pauli Virtanen]

There is theoretical UAF if the conn is freed while the hci_sync task
is running.

Hold refcount to avoid that.

Fixes: 881559af5f5c ("Bluetooth: hci_sync: Attempt to dequeue connection attempt")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
---

Notes:
    v5:
    - no change
    v4:
    - no change
    v3:
    - split to multiple patches per different Fixes:
    
    hci_conn_get() was added inside hci_le_create_conn_sync()
    in commit 76c2d047410ba, but it is too late to do there as the
    hci_conn_get() itself may be UAF.

 net/bluetooth/hci_sync.c | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index d5554fbf3129..83efca415eaf 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -7128,12 +7128,23 @@ static int hci_acl_create_conn_sync(struct hci_dev *hdev, void *data)
 	return err;
 }
 
+static void hci_acl_create_conn_sync_complete(struct hci_dev *hdev, void *data,
+					      int err)
+{
+	struct hci_conn *conn = data;
+
+	hci_conn_put(conn);
+}
+
 int hci_connect_acl_sync(struct hci_dev *hdev, struct hci_conn *conn)
 {
 	int err;
 
-	err = hci_cmd_sync_queue_once(hdev, hci_acl_create_conn_sync, conn,
-				      NULL);
+	err = hci_cmd_sync_queue_once(hdev, hci_acl_create_conn_sync,
+				      hci_conn_get(conn),
+				      hci_acl_create_conn_sync_complete);
+	if (err)
+		hci_conn_put(conn);
 	return (err == -EEXIST) ? 0 : err;
 }
 
@@ -7144,36 +7155,41 @@ static void create_le_conn_complete(struct hci_dev *hdev, void *data, int err)
 	bt_dev_dbg(hdev, "err %d", err);
 
 	if (err == -ECANCELED)
-		return;
+		goto done;
 
 	hci_dev_lock(hdev);
 
 	if (!hci_conn_valid(hdev, conn))
-		goto done;
+		goto unlock;
 
 	if (!err) {
 		hci_connect_le_scan_cleanup(conn, 0x00);
-		goto done;
+		goto unlock;
 	}
 
 	/* Check if connection is still pending */
 	if (conn != hci_lookup_le_connect(hdev))
-		goto done;
+		goto unlock;
 
 	/* Flush to make sure we send create conn cancel command if needed */
 	flush_delayed_work(&conn->le_conn_timeout);
 	hci_conn_failed(conn, bt_status(err));
 
-done:
+unlock:
 	hci_dev_unlock(hdev);
+done:
+	hci_conn_put(conn);
 }
 
 int hci_connect_le_sync(struct hci_dev *hdev, struct hci_conn *conn)
 {
 	int err;
 
-	err = hci_cmd_sync_queue_once(hdev, hci_le_create_conn_sync, conn,
+	err = hci_cmd_sync_queue_once(hdev, hci_le_create_conn_sync,
+				      hci_conn_get(conn),
 				      create_le_conn_complete);
+	if (err)
+		hci_conn_put(conn);
 	return (err == -EEXIST) ? 0 : err;
 }
 
-- 
2.55.0

[PATCH v5 3/7] Bluetooth: hci_sync: hold conn in hci_connect_big_sync() callback

[Pauli Virtanen]

There is theoretical UAF if the conn is freed while the hci_sync task is
running.

Hold refcount to avoid that. Handle NULL hcon, return 0 + do nothing to
match the previous behavior.

Fixes: 024421cf3992 ("Bluetooth: hci_conn: Fix not setting timeout for BIG Create Sync")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
---

Notes:
    v5:
    - clear_bit() without hci_conn_valid check, we hold reference
    v4:
    - check for conn == NULL before hci_conn_get(), since it appears
      iso.c may end up calling this with NULL
    v3:
    - split to multiple patches per different Fixes:
    - hold RCU instead of hdev->lock

 net/bluetooth/hci_sync.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 83efca415eaf..5610ef00fd0f 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -7498,10 +7498,12 @@ static void create_big_complete(struct hci_dev *hdev, void *data, int err)
 	bt_dev_dbg(hdev, "err %d", err);
 
 	if (err == -ECANCELED)
-		return;
+		goto done;
 
-	if (hci_conn_valid(hdev, conn))
-		clear_bit(HCI_CONN_CREATE_BIG_SYNC, &conn->flags);
+	clear_bit(HCI_CONN_CREATE_BIG_SYNC, &conn->flags);
+
+done:
+	hci_conn_put(conn);
 }
 
 static int hci_le_big_create_sync(struct hci_dev *hdev, void *data)
@@ -7553,8 +7555,14 @@ int hci_connect_big_sync(struct hci_dev *hdev, struct hci_conn *conn)
 {
 	int err;
 
-	err = hci_cmd_sync_queue_once(hdev, hci_le_big_create_sync, conn,
+	if (!conn)
+		return 0;
+
+	err = hci_cmd_sync_queue_once(hdev, hci_le_big_create_sync,
+				      hci_conn_get(conn),
 				      create_big_complete);
+	if (err)
+		hci_conn_put(conn);
 	return (err == -EEXIST) ? 0 : err;
 }
 
-- 
2.55.0

[PATCH v5 4/7] Bluetooth: hci_sync: hold conn in hci_connect_pa_sync() callback

[Pauli Virtanen]

There is theoretical UAF if the conn is freed while the hci_sync task is
running.

Hold refcount to avoid that.

Fixes: 6d0417e4e1cf ("Bluetooth: hci_conn: Fix not setting conn_timeout for Broadcast Receiver")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
---

Notes:
    v5:
    - no change
    v4:
    - no change
    v3:
    - split to multiple patches per different Fixes:

 net/bluetooth/hci_sync.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 5610ef00fd0f..86c865306d21 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -7312,7 +7312,7 @@ static void create_pa_complete(struct hci_dev *hdev, void *data, int err)
 	bt_dev_dbg(hdev, "err %d", err);
 
 	if (err == -ECANCELED)
-		return;
+		goto done;
 
 	hci_dev_lock(hdev);
 
@@ -7336,6 +7336,8 @@ static void create_pa_complete(struct hci_dev *hdev, void *data, int err)
 
 unlock:
 	hci_dev_unlock(hdev);
+done:
+	hci_conn_put(conn);
 }
 
 static int hci_le_past_params_sync(struct hci_dev *hdev, struct hci_conn *conn,
@@ -7486,8 +7488,11 @@ int hci_connect_pa_sync(struct hci_dev *hdev, struct hci_conn *conn)
 {
 	int err;
 
-	err = hci_cmd_sync_queue_once(hdev, hci_le_pa_create_sync, conn,
+	err = hci_cmd_sync_queue_once(hdev, hci_le_pa_create_sync,
+				      hci_conn_get(conn),
 				      create_pa_complete);
+	if (err)
+		hci_conn_put(conn);
 	return (err == -EEXIST) ? 0 : err;
 }
 
-- 
2.55.0

[PATCH v5 5/7] Bluetooth: hci_sync: hold conn in hci_past_sync() callback

[Pauli Virtanen]

Avoids giving freed pointers to hci_conn_valid(), which kmalloc may have
reused.

Hold refcount to avoid that.

Fixes: d3413703d5f8 ("Bluetooth: ISO: Add support to bind to trigger PAST")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
---

Notes:
    v5:
    - no change
    v4:
    - no change
    v3:
    - split to multiple patches per different Fixes:

 net/bluetooth/hci_sync.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 86c865306d21..63d0b89a88f3 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -7582,6 +7582,8 @@ static void past_complete(struct hci_dev *hdev, void *data, int err)
 
 	bt_dev_dbg(hdev, "err %d", err);
 
+	hci_conn_put(past->conn);
+	hci_conn_put(past->le);
 	kfree(past);
 }
 
@@ -7646,8 +7648,8 @@ int hci_past_sync(struct hci_conn *conn, struct hci_conn *le)
 	if (!data)
 		return -ENOMEM;
 
-	data->conn = conn;
-	data->le = le;
+	data->conn = hci_conn_get(conn);
+	data->le = hci_conn_get(le);
 
 	if (conn->role == HCI_ROLE_MASTER)
 		err = hci_cmd_sync_queue_once(conn->hdev,
@@ -7657,8 +7659,11 @@ int hci_past_sync(struct hci_conn *conn, struct hci_conn *le)
 		err = hci_cmd_sync_queue_once(conn->hdev, hci_le_past_sync,
 					      data, past_complete);
 
-	if (err)
+	if (err) {
+		hci_conn_put(data->conn);
+		hci_conn_put(data->le);
 		kfree(data);
+	}
 
 	return (err == -EEXIST) ? 0 : err;
 }
-- 
2.55.0

[PATCH v5 6/7] Bluetooth: hci_sync: fix hci_conn_del() use in hci_le_create_conn_sync

[Pauli Virtanen]

hci_conn_del() caller must hold hdev->lock, check the conn was not
concurrently deleted, and usually inform socket the conn is going to be
deleted.

Use hci_abort_conn_sync() instead of calling hci_conn_del() without
locks etc.

Fixes: 8e8b92ee60de5 ("Bluetooth: hci_sync: Add hci_le_create_conn_sync")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
---

Notes:
    v5:
    - no change
    v4:
    - no change
    v3:
    - use hci_abort_conn_sync instead of lock + hci_conn_valid + hci_conn_del

 net/bluetooth/hci_sync.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 63d0b89a88f3..0f76221db2bd 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -6733,7 +6733,9 @@ static int hci_le_create_conn_sync(struct hci_dev *hdev, void *data)
 		if (hci_dev_test_flag(hdev, HCI_LE_SCAN) &&
 		    hdev->le_scan_type == LE_SCAN_ACTIVE &&
 		    !hci_dev_test_flag(hdev, HCI_LE_SIMULTANEOUS_ROLES)) {
-			hci_conn_del(conn);
+			conn->state = BT_OPEN;
+			hci_abort_conn_sync(hdev, conn,
+					    HCI_ERROR_REJ_LIMITED_RESOURCES);
 			hci_conn_put(conn);
 			return -EBUSY;
 		}
-- 
2.55.0

[PATCH v5 7/7] Bluetooth: hci_sync: remove unnecessary hci_conn_get in create_conn_sync

[Pauli Virtanen]

hci_conn_get() without already held reference is data race against
concurrent deletion.

In previous patches, the refcount has been changed to be taken before
starting the hci_sync task, so remove these extra get() + put() as they
are not needed.

Fixes: 76c2d047410ba ("Bluetooth: hci_conn: Fix null ptr deref in hci_abort_conn()")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
---

Notes:
    v5:
    - no change
    v4:
    - no change

 net/bluetooth/hci_sync.c | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 0f76221db2bd..7779d9d1663a 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -6717,11 +6717,6 @@ static int hci_le_create_conn_sync(struct hci_dev *hdev, void *data)
 
 	bt_dev_dbg(hdev, "conn %p", conn);
 
-	/* Hold a reference so conn stays valid for the HCI_CONN_CREATE
-	 * clear_bit() at done.
-	 */
-	hci_conn_get(conn);
-
 	clear_bit(HCI_CONN_SCANNING, &conn->flags);
 	conn->state = BT_CONNECT;
 
@@ -6736,7 +6731,6 @@ static int hci_le_create_conn_sync(struct hci_dev *hdev, void *data)
 			conn->state = BT_OPEN;
 			hci_abort_conn_sync(hdev, conn,
 					    HCI_ERROR_REJ_LIMITED_RESOURCES);
-			hci_conn_put(conn);
 			return -EBUSY;
 		}
 
@@ -6834,7 +6828,6 @@ static int hci_le_create_conn_sync(struct hci_dev *hdev, void *data)
 
 	/* Re-enable advertising after the connection attempt is finished. */
 	hci_resume_advertising_sync(hdev);
-	hci_conn_put(conn);
 	return err;
 }
 
@@ -7109,11 +7102,6 @@ static int hci_acl_create_conn_sync(struct hci_dev *hdev, void *data)
 	else
 		cp.role_switch = 0x00;
 
-	/* Hold a reference so conn stays valid for the HCI_CONN_CREATE
-	 * clear_bit() below.
-	 */
-	hci_conn_get(conn);
-
 	/* Mark create connection in flight so hci_cancel_connect_sync() can
 	 * cancel it while blocking on the connection complete event.
 	 */
@@ -7125,7 +7113,6 @@ static int hci_acl_create_conn_sync(struct hci_dev *hdev, void *data)
 				       conn->conn_timeout, NULL);
 
 	clear_bit(HCI_CONN_CREATE, &conn->flags);
-	hci_conn_put(conn);
 
 	return err;
 }
-- 
2.55.0