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Wed, 01 Apr 2026 07:26:00 -0700 (PDT) From: Keenan Dong To: linux-bluetooth@vger.kernel.org Cc: marcel@holtmann.org, luiz.dentz@gmail.com, linux-kernel@vger.kernel.org, Keenan Dong Subject: [PATCH v2] Bluetooth: MGMT: validate mesh send advertising payload length Date: Wed, 1 Apr 2026 22:25:26 +0800 Message-ID: <20260401142532.332943-1-keenanat2000@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260328084648.51158-2-keenanat2000@gmail.com> References: <20260328084648.51158-2-keenanat2000@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" mesh_send() currently bounds MGMT_OP_MESH_SEND by total command length, but it never verifies that the bytes supplied for the flexible adv_data[] array actually match the embedded adv_data_len field. MGMT_MESH_SEND_SIZE only covers the fixed header, so a truncated command can still pass the existing 20..50 byte range check and later drive the async mesh send path past the end of the queued command buffer. Keep rejecting zero-length and oversized advertising payloads, but validate adv_data_len explicitly and require the command length to exactly match the flexible array size before queueing the request. Fixes: b338d91703fa ("Bluetooth: Implement support for Mesh") Reported-by: Keenan Dong Signed-off-by: Keenan Dong --- v2: - replace the raw total-length range check in mesh_send() - keep REJECTED for zero-length and oversized advertising payloads - reject len/adv_data_len desynchronization with INVALID_PARAMS Validation: - vuln kernel reproduced the field-spanning write in hci_set_adv_instance_data() with a minimal direct-QEMU initramfs repro - fixed kernel rejected malformed MGMT_OP_MESH_SEND requests at ingress in the same direct-QEMU setup net/bluetooth/mgmt.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c index e5f9287fb..18cee19aa 100644 --- a/net/bluetooth/mgmt.c +++ b/net/bluetooth/mgmt.c @@ -2478,6 +2478,7 @@ static int mesh_send(struct sock *sk, struct hci_dev = *hdev, void *data, u16 len) struct mgmt_mesh_tx *mesh_tx; struct mgmt_cp_mesh_send *send =3D data; struct mgmt_rp_mesh_read_features rp; + u16 expected_len; bool sending; int err =3D 0; =20 @@ -2485,12 +2486,19 @@ static int mesh_send(struct sock *sk, struct hci_de= v *hdev, void *data, u16 len) !hci_dev_test_flag(hdev, HCI_MESH_EXPERIMENTAL)) return mgmt_cmd_status(sk, hdev->id, MGMT_OP_MESH_SEND, MGMT_STATUS_NOT_SUPPORTED); - if (!hci_dev_test_flag(hdev, HCI_LE_ENABLED) || - len <=3D MGMT_MESH_SEND_SIZE || - len > (MGMT_MESH_SEND_SIZE + 31)) + if (!hci_dev_test_flag(hdev, HCI_LE_ENABLED)) + return mgmt_cmd_status(sk, hdev->id, MGMT_OP_MESH_SEND, + MGMT_STATUS_REJECTED); + + if (!send->adv_data_len || send->adv_data_len > 31) return mgmt_cmd_status(sk, hdev->id, MGMT_OP_MESH_SEND, MGMT_STATUS_REJECTED); =20 + expected_len =3D struct_size(send, adv_data, send->adv_data_len); + if (expected_len !=3D len) + return mgmt_cmd_status(sk, hdev->id, MGMT_OP_MESH_SEND, + MGMT_STATUS_INVALID_PARAMS); + hci_dev_lock(hdev); =20 memset(&rp, 0, sizeof(rp)); --=20 2.43.0