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Fri, 07 Aug 2026 03:15:43 -0700 (PDT) From: Baul Lee To: Luiz Augusto von Dentz , Marcel Holtmann , Brian Gix Cc: Baul Lee , Luiz Augusto von Dentz , Dmitry Antipov , linux-bluetooth@vger.kernel.org, linux-kernel@vger.kernel.org, federico.kirschbaum@xbow.com, stable@vger.kernel.org Subject: [PATCH v2 2/3] Bluetooth: MGMT: protect hdev->mesh_pending with hdev->lock Date: Fri, 7 Aug 2026 19:15:28 +0900 Message-ID: <20260807101529.17348-3-baul.lee@xbow.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260807101529.17348-1-baul.lee@xbow.com> References: <20260807101529.17348-1-baul.lee@xbow.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit hdev->mesh_pending carries the queued struct mgmt_mesh_tx of the mesh mgmt interface. It is extended and walked from syscall context under hci_dev_lock(hdev), in mgmt_mesh_add() and mgmt_mesh_foreach(), and it is unlinked and freed from the hci_cmd_sync worker under hci_req_sync_lock(hdev), in send_cancel(), mesh_send_done_sync() and mesh_next(). The two sides hold different mutexes, so the list has no protection: MGMT_OP_MESH_READ_FEATURES on one socket can be mid-walk while MGMT_OP_MESH_SEND_CANCEL on another frees the entry it is standing on. [ 47.418949] BUG: KASAN: slab-use-after-free in send_count+0x4c/0x6c [ 47.419029] Read of size 1 at addr ffff000015943228 by task c2_race/191 [ 47.419546] send_count+0x4c/0x6c [ 47.419591] mgmt_mesh_foreach+0x68/0x100 [ 47.419637] mesh_features+0x180/0x184 [ 47.421345] Freed by task 59: [ 47.421555] mgmt_mesh_remove+0x94/0x110 [ 47.421589] send_cancel+0xd8/0x1cc [ 47.421627] hci_cmd_sync_work+0xac/0x128 Offset 40 of the freed 96-byte object is mesh_tx->handle, the byte send_count() puts in the MESH_READ_FEATURES reply. The walk also follows the LIST_POISON1 left by the concurrent list_del(), which oopses with hci_dev_lock held and never released, so every later mgmt command on that controller blocks. The same missing lock lets the worker free the object under mesh_send(), which reads mesh_tx->handle into the command complete after queueing: [ 41.093914] BUG: KASAN: slab-use-after-free in mgmt_cmd_complete+0xd0/0x210 [ 41.094353] Read of size 1 at addr ffff00000a0dea28 by task c1_poc/162 [ 41.096944] mgmt_mesh_remove+0x94/0x110 [ 41.096975] mesh_send_start_complete+0x128/0x160 That read already sits inside mesh_send()'s hci_dev_lock() section; it is the worker side that is missing the lock. Take hci_dev_lock(hdev) on the worker side, around the list work only and not around hci_disable_advertising_sync(), and assert it in the helpers that walk or extend the list. hci_req_sync_lock -> hdev->lock is the order this subsystem already uses: hci_cmd_sync_work() calls entry->func under req_lock, and callbacks such as hci_update_eir_sync() take hci_dev_lock() inside it. mesh_next() and mesh_send_start_complete() are destroy callbacks, and hci_cmd_sync_clear() runs a destroy callback under cmd_sync_work_lock, which every mgmt caller of hci_cmd_sync_queue() takes with hdev->lock already held. Both therefore return before hci_dev_lock() when err is -ECANCELED, as the other destroy callbacks in this file do. Without those returns lockdep reports a circular dependency, reached by closing /dev/vhci while a mesh entry is queued behind a parked req_workqueue: [ 78.211873] ffff00001b0340b8 (&hdev->lock){+.+.}-{4:4}, at: mesh_send_start_complete+0x88/0xf4 but task is already holding lock: [ 78.212596] ffff00001b0347c0 (&hdev->cmd_sync_work_lock){+.+.}-{4:4}, at: hci_cmd_sync_clear+0x60/0xd4 -> #1 (&hdev->cmd_sync_work_lock){+.+.}-{4:4}: [ 78.214268] hci_update_passive_scan+0x6c/0x84 [ 78.214455] mgmt_set_powered_complete+0x1b0/0x1f8 The other leg of the cycle, mgmt_set_powered_complete() calling hci_update_passive_scan() with hdev->lock held, is an existing in-tree path. The entry such a return leaves on hdev->mesh_pending stays there, as entries already do across an unregister. Discovered by XBOW, triaged by Baul Lee Fixes: b338d91703fa ("Bluetooth: Implement support for Mesh") Fixes: 3bb88524b7d0 ("Bluetooth: MGMT: iterate over mesh commands in mgmt_mesh_foreach()") Cc: stable@vger.kernel.org Signed-off-by: Baul Lee --- net/bluetooth/mgmt.c | 30 ++++++++++++++++++++++++++++-- net/bluetooth/mgmt_util.c | 8 ++++++++ 2 files changed, 36 insertions(+), 2 deletions(-) diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c index 97408904f74b..853a80fd15af 100644 --- a/net/bluetooth/mgmt.c +++ b/net/bluetooth/mgmt.c @@ -1087,6 +1087,8 @@ static void mesh_send_complete(struct hci_dev *hdev, { u8 handle = mesh_tx->handle; + lockdep_assert_held(&hdev->lock); + if (!silent) mgmt_event(MGMT_EV_MESH_PACKET_CMPLT, hdev, &handle, sizeof(handle), NULL); @@ -1101,11 +1103,16 @@ static int mesh_send_done_sync(struct hci_dev *hdev, void *data) hci_dev_clear_flag(hdev, HCI_MESH_SENDING); if (list_empty(&hdev->adv_instances)) hci_disable_advertising_sync(hdev); + + hci_dev_lock(hdev); + mesh_tx = mgmt_mesh_next(hdev, NULL); if (mesh_tx) mesh_send_complete(hdev, mesh_tx, false); + hci_dev_unlock(hdev); + return 0; } @@ -1113,11 +1120,19 @@ static int mesh_send_sync(struct hci_dev *hdev, void *data); static void mesh_send_start_complete(struct hci_dev *hdev, void *data, int err); static void mesh_next(struct hci_dev *hdev, void *data, int err) { - struct mgmt_mesh_tx *mesh_tx = mgmt_mesh_next(hdev, NULL); + struct mgmt_mesh_tx *mesh_tx; - if (!mesh_tx) + if (err == -ECANCELED) return; + hci_dev_lock(hdev); + + mesh_tx = mgmt_mesh_next(hdev, NULL); + if (!mesh_tx) { + hci_dev_unlock(hdev); + return; + } + err = hci_cmd_sync_queue(hdev, mesh_send_sync, mesh_tx, mesh_send_start_complete); @@ -1125,6 +1140,8 @@ static void mesh_next(struct hci_dev *hdev, void *data, int err) mesh_send_complete(hdev, mesh_tx, false); else hci_dev_set_flag(hdev, HCI_MESH_SENDING); + + hci_dev_unlock(hdev); } static void mesh_send_done(struct work_struct *work) @@ -2310,12 +2327,17 @@ static void mesh_send_start_complete(struct hci_dev *hdev, void *data, int err) unsigned long mesh_send_interval; u8 mgmt_err = mgmt_status(err); + if (err == -ECANCELED) + return; + /* Report any errors here, but don't report completion */ if (mgmt_err) { hci_dev_clear_flag(hdev, HCI_MESH_SENDING); /* Send Complete Error Code for handle */ + hci_dev_lock(hdev); mesh_send_complete(hdev, mesh_tx, false); + hci_dev_unlock(hdev); return; } @@ -2421,6 +2443,8 @@ static int send_cancel(struct hci_dev *hdev, void *data) struct mgmt_cp_mesh_send_cancel *cancel = (void *)cmd->param; struct mgmt_mesh_tx *mesh_tx; + hci_dev_lock(hdev); + if (!cancel->handle) { do { mesh_tx = mgmt_mesh_next(hdev, cmd->sk); @@ -2435,6 +2459,8 @@ static int send_cancel(struct hci_dev *hdev, void *data) mesh_send_complete(hdev, mesh_tx, false); } + hci_dev_unlock(hdev); + mgmt_cmd_complete(cmd->sk, hdev->id, MGMT_OP_MESH_SEND_CANCEL, 0, NULL, 0); diff --git a/net/bluetooth/mgmt_util.c b/net/bluetooth/mgmt_util.c index 6ea107c0e054..a822091f2907 100644 --- a/net/bluetooth/mgmt_util.c +++ b/net/bluetooth/mgmt_util.c @@ -369,6 +369,8 @@ void mgmt_mesh_foreach(struct hci_dev *hdev, { struct mgmt_mesh_tx *mesh_tx, *tmp; + lockdep_assert_held(&hdev->lock); + list_for_each_entry_safe(mesh_tx, tmp, &hdev->mesh_pending, list) { if (!sk || mesh_tx->sk == sk) cb(mesh_tx, data); @@ -379,6 +381,8 @@ struct mgmt_mesh_tx *mgmt_mesh_next(struct hci_dev *hdev, struct sock *sk) { struct mgmt_mesh_tx *mesh_tx; + lockdep_assert_held(&hdev->lock); + if (list_empty(&hdev->mesh_pending)) return NULL; @@ -394,6 +398,8 @@ struct mgmt_mesh_tx *mgmt_mesh_find(struct hci_dev *hdev, u8 handle) { struct mgmt_mesh_tx *mesh_tx; + lockdep_assert_held(&hdev->lock); + if (list_empty(&hdev->mesh_pending)) return NULL; @@ -410,6 +416,8 @@ struct mgmt_mesh_tx *mgmt_mesh_add(struct sock *sk, struct hci_dev *hdev, { struct mgmt_mesh_tx *mesh_tx; + lockdep_assert_held(&hdev->lock); + mesh_tx = kzalloc_obj(*mesh_tx); if (!mesh_tx) return NULL; -- 2.50.1 (Apple Git-155)