[PATCH] Bluetooth: MGMT: require exact mesh send payload length

[Keenan Dong <keenanat2000@gmail.com>]

mesh_send() only checks that the total command length falls within a
broad range. A malformed MGMT_OP_MESH_SEND request can therefore claim
a larger adv_data_len than the bytes actually present, and the async
mesh send path later copies past the end of the stored command buffer.

Require the command length to exactly match the variable advertising
payload size before queueing the request.

Fixes: b338d91703fa ("Bluetooth: Implement support for Mesh")
Reported-by: Keenan Dong <keenanat2000@gmail.com>
Signed-off-by: Keenan Dong <keenanat2000@gmail.com>
---
 net/bluetooth/mgmt.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
index e5f9287fb..aad0da033 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 = data;
 	struct mgmt_rp_mesh_read_features rp;
+	u16 expected_len;
 	bool sending;
 	int err = 0;
 
@@ -2491,6 +2492,11 @@ static int mesh_send(struct sock *sk, struct hci_dev *hdev, void *data, u16 len)
 		return mgmt_cmd_status(sk, hdev->id, MGMT_OP_MESH_SEND,
 				       MGMT_STATUS_REJECTED);
 
+	expected_len = struct_size(send, adv_data, send->adv_data_len);
+	if (expected_len != len)
+		return mgmt_cmd_status(sk, hdev->id, MGMT_OP_MESH_SEND,
+				       MGMT_STATUS_INVALID_PARAMS);
+
 	hci_dev_lock(hdev);
 
 	memset(&rp, 0, sizeof(rp));
-- 
2.43.0