be2net: Fix buffer overflow in be_get_module_eeprom

be_cmd_read_port_transceiver_data assumes that it is given a buffer that
is at least PAGE_DATA_LEN long, or twice that if the module supports SFF
8472. However, this is not always the case.

Fix this by passing the desired offset and length to
be_cmd_read_port_transceiver_data so that we only copy the bytes once.

Fixes: e36edd9d26cf ("be2net: add ethtool "-m" option support")
Signed-off-by: Hristo Venev <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Paolo Abeni <[e-mail]>

drivers/net/ethernet/emulex/benet/be_cmds.c

···
 
 /* Uses sync mcc */
 int be_cmd_read_port_transceiver_data(struct be_adapter *adapter,
-				      u8 page_num, u8 *data)
+				      u8 page_num, u32 off, u32 len, u8 *data)
 {
 	struct be_dma_mem cmd;
 	struct be_mcc_wrb *wrb;
···
 	req->port = cpu_to_le32(adapter->hba_port_num);
 	req->page_num = cpu_to_le32(page_num);
 	status = be_mcc_notify_wait(adapter);
-	if (!status) {
+	if (!status && len > 0) {
 		struct be_cmd_resp_port_type *resp = cmd.va;
 
-		memcpy(data, resp->page_data, PAGE_DATA_LEN);
+		memcpy(data, resp->page_data + off, len);
 	}
 err:
 	mutex_unlock(&adapter->mcc_lock);
···
 	int status;
 
 	status = be_cmd_read_port_transceiver_data(adapter, TR_PAGE_A0,
-						   page_data);
+						   0, PAGE_DATA_LEN, page_data);
 	if (!status) {
 		switch (adapter->phy.interface_type) {
 		case PHY_TYPE_QSFP:
···
 	int status;
 
 	status = be_cmd_read_port_transceiver_data(adapter, TR_PAGE_A0,
-						   page_data);
+						   0, PAGE_DATA_LEN, page_data);
 	if (!status) {
 		strlcpy(adapter->phy.vendor_name, page_data +
 			SFP_VENDOR_NAME_OFFSET, SFP_VENDOR_NAME_LEN - 1);

drivers/net/ethernet/emulex/benet/be_cmds.h

···
 int be_cmd_get_beacon_state(struct be_adapter *adapter, u8 port_num,
 			    u32 *state);
 int be_cmd_read_port_transceiver_data(struct be_adapter *adapter,
-				      u8 page_num, u8 *data);
+				      u8 page_num, u32 off, u32 len, u8 *data);
 int be_cmd_query_cable_type(struct be_adapter *adapter);
 int be_cmd_query_sfp_info(struct be_adapter *adapter);
 int lancer_cmd_read_object(struct be_adapter *adapter, struct be_dma_mem *cmd,

drivers/net/ethernet/emulex/benet/be_ethtool.c

···
 		return -EOPNOTSUPP;
 
 	status = be_cmd_read_port_transceiver_data(adapter, TR_PAGE_A0,
-						   page_data);
+						   0, PAGE_DATA_LEN, page_data);
 	if (!status) {
 		if (!page_data[SFP_PLUS_SFF_8472_COMP]) {
 			modinfo->type = ETH_MODULE_SFF_8079;
···
 {
 	struct be_adapter *adapter = netdev_priv(netdev);
 	int status;
+	u32 begin, end;
 
 	if (!check_privilege(adapter, MAX_PRIVILEGES))
 		return -EOPNOTSUPP;
 
-	status = be_cmd_read_port_transceiver_data(adapter, TR_PAGE_A0,
-						   data);
-	if (status)
-		goto err;
+	begin = eeprom->offset;
+	end = eeprom->offset + eeprom->len;
 
-	if (eeprom->offset + eeprom->len > PAGE_DATA_LEN) {
-		status = be_cmd_read_port_transceiver_data(adapter,
-							   TR_PAGE_A2,
-							   data +
-							   PAGE_DATA_LEN);
+	if (begin < PAGE_DATA_LEN) {
+		status = be_cmd_read_port_transceiver_data(adapter, TR_PAGE_A0, begin,
+							   min_t(u32, end, PAGE_DATA_LEN) - begin,
+							   data);
+		if (status)
+			goto err;
+
+		data += PAGE_DATA_LEN - begin;
+		begin = PAGE_DATA_LEN;
+	}
+
+	if (end > PAGE_DATA_LEN) {
+		status = be_cmd_read_port_transceiver_data(adapter, TR_PAGE_A2,
+							   begin - PAGE_DATA_LEN,
+							   end - begin, data);
 		if (status)
 			goto err;
 	}
-	if (eeprom->offset)
-		memcpy(data, data + eeprom->offset, eeprom->len);
 err:
 	return be_cmd_status(status);
 }