[PATCH] Bluetooth: hci_aml: validate firmware segment lengths

[Laxman Acharya Padhya]

aml_download_firmware() reads two lengths from the firmware header and
uses them to build pointers before checking that the header and segment
data are present. A truncated or inconsistent firmware image can make
the driver read past firmware->data while constructing TCI commands.

Reject images shorter than the header and ensure that the ICCM and DCCM
ranges fit within the loaded firmware before downloading either segment.

Fixes: 37bac77e4649 ("Bluetooth: hci_uart: Add support for Amlogic HCI UART")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Laxman Acharya Padhya <acharyalaxman8848@xxxxxxxxx>
---
 drivers/bluetooth/hci_aml.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/bluetooth/hci_aml.c b/drivers/bluetooth/hci_aml.c
index 959d9e67b..067fbf278 100644
--- a/drivers/bluetooth/hci_aml.c
+++ b/drivers/bluetooth/hci_aml.c
@@ -247,7 +247,7 @@ static int aml_download_firmware(struct hci_dev *hdev, const char *fw_name)
 	struct hci_uart *hu = hci_get_drvdata(hdev);
 	struct aml_serdev *amldev = serdev_device_get_drvdata(hu->serdev);
 	const struct firmware *firmware = NULL;
-	struct aml_fw_len *fw_len = NULL;
+	const struct aml_fw_len *fw_len = NULL;
 	u8 *iccm_start = NULL, *dccm_start = NULL;
 	u32 iccm_len, dccm_len;
 	u32 value = 0;
@@ -281,7 +281,21 @@ static int aml_download_firmware(struct hci_dev *hdev, const char *fw_name)
 		goto exit;
 	}
 
-	fw_len = (struct aml_fw_len *)firmware->data;
+	if (firmware->size < sizeof(*fw_len)) {
+		bt_dev_err(hdev, "Firmware is too small for its header");
+		ret = -EINVAL;
+		goto exit;
+	}
+
+	fw_len = (const struct aml_fw_len *)firmware->data;
+	if (fw_len->iccm_len < amldev->aml_dev_data->iccm_offset ||
+	    fw_len->iccm_len > firmware->size - sizeof(*fw_len) ||
+	    fw_len->dccm_len > firmware->size - sizeof(*fw_len) -
+			fw_len->iccm_len) {
+		bt_dev_err(hdev, "Invalid firmware segment lengths");
+		ret = -EINVAL;
+		goto exit;
+	}
 
 	/* Download ICCM */
 	iccm_start = (u8 *)(firmware->data) + sizeof(struct aml_fw_len)
-- 
2.51.2