On Mon, Jan 22, 2024 at 10:45:28AM +0200, Danielle Ratson wrote:
...
> +/**
> + * struct ethtool_cmis_cdb_request - CDB commands request fields as decribed in
> + * the CMIS standard
> + * @id: Command ID.
> + * @epl_len: EPL memory length.
> + * @lpl_len: LPL memory length.
> + * @chk_code: Check code for the previous field and the payload.
> + * @resv1: Added to match the CMIS standard request continuity.
> + * @resv2: Added to match the CMIS standard request continuity.
> + * @payload: Payload for the CDB commands.
> + */
> +struct ethtool_cmis_cdb_request {
> + __be16 id;
> + struct_group(body,
> + u16 epl_len;
> + u8 lpl_len;
> + u8 chk_code;
> + u8 resv1;
> + u8 resv2;
> + u8 payload[ETHTOOL_CMIS_CDB_LPL_MAX_PL_LENGTH];
> + );
> +};
> +
> +#define CDB_F_COMPLETION_VALID BIT(0)
> +#define CDB_F_STATUS_VALID BIT(1)
> +
> +/**
> + * struct ethtool_cmis_cdb_cmd_args - CDB commands execution arguments
> + * @req: CDB command fields as described in the CMIS standard.
> + * @max_duration: Maximum duration time for command completion in msec.
> + * @read_write_len_ext: Allowable additional number of byte octets to the LPL
> + * in a READ or a WRITE commands.
> + * @rpl_exp_len: Expected reply length in bytes.
> + * @flags: Validation flags for CDB commands.
> + */
> +struct ethtool_cmis_cdb_cmd_args {
> + struct ethtool_cmis_cdb_request req;
> + u16 max_duration;
> + u8 read_write_len_ext;
> + u8 rpl_exp_len;
> + u8 flags;
> +};
...
> +int ethtool_cmis_page_init(struct ethtool_module_eeprom *page_data,
> + u8 page, u32 offset, u32 length)
> +{
> + page_data->page = page;
> + page_data->offset = offset;
> + page_data->length = length;
> + page_data->i2c_address = ETHTOOL_CMIS_CDB_PAGE_I2C_ADDR;
> + page_data->data = kmalloc(page_data->length, GFP_KERNEL);
> + if (!page_data->data)
> + return -ENOMEM;
> +
> + return 0;
> +}
...
> +static int
> +__ethtool_cmis_cdb_execute_cmd(struct net_device *dev,
> + struct ethtool_module_eeprom *page_data,
> + u32 offset, u32 length, void *data)
> +{
> + const struct ethtool_ops *ops = dev->ethtool_ops;
> + struct netlink_ext_ack extack = {};
> + int err;
> +
> + page_data->offset = offset;
> + page_data->length = length;
> +
> + memset(page_data->data, 0, ETHTOOL_CMIS_CDB_LPL_MAX_PL_LENGTH);
> + memcpy(page_data->data, data, page_data->length);
> +
> + err = ops->set_module_eeprom_by_page(dev, page_data, &extack);
> + if (err < 0) {
> + if (extack._msg)
> + netdev_err(dev, "%s\n", extack._msg);
> + }
> +
> + return err;
> +}
...
> +int ethtool_cmis_cdb_execute_cmd(struct net_device *dev,
> + struct ethtool_cmis_cdb_cmd_args *args)
> +{
> + struct ethtool_module_eeprom page_data = {};
> + u32 offset;
> + int err;
> +
> + args->req.chk_code =
> + cmis_cdb_calc_checksum(&args->req, sizeof(args->req));
> +
> + if (args->req.lpl_len > args->read_write_len_ext) {
> + ethnl_module_fw_flash_ntf_err(dev,
> + "LPL length is longer than CDB read write length extension allows");
> + return -EINVAL;
> + }
> +
> + err = ethtool_cmis_page_init(&page_data, ETHTOOL_CMIS_CDB_CMD_PAGE, 0,
> + ETHTOOL_CMIS_CDB_LPL_MAX_PL_LENGTH);
ETHTOOL_CMIS_CDB_LPL_MAX_PL_LENGTH is passed as the length argument
of ethtool_cmis_page_init, which will allocate that many
bytes for page_data->data.
> + if (err < 0)
> + return err;
> +
> + /* According to the CMIS standard, there are two options to trigger the
> + * CDB commands. The default option is triggering the command by writing
> + * the CMDID bytes. Therefore, the command will be split to 2 calls:
> + * First, with everything except the CMDID field and then the CMDID
> + * field.
> + */
> + offset = CMIS_CDB_CMD_ID_OFFSET +
> + offsetof(struct ethtool_cmis_cdb_request, body);
> + err = __ethtool_cmis_cdb_execute_cmd(dev, &page_data, offset,
> + sizeof(args->req.body),
> + &args->req.body);
Hi Danielle,
However, here sizeof(args->req.body) is passed as the length
argument of __ethtool_cmis_cdb_execute_cmd() which will:
1. Zero ETHTOOL_CMIS_CDB_LPL_MAX_PL_LENGTH bytes of page_data->data
2. Copy sizeof(args->req.body) bytes into page_data->data
args->req.body includes several fields, one of which is
ETHTOOL_CMIS_CDB_LPL_MAX_PL_LENGTH bytes long. So,
args->req.body > ETHTOOL_CMIS_CDB_LPL_MAX_PL_LENGTH
and it seems that step 2 above causes a buffer overrun.
Flagged by clang-17 W=1 build
In file included from net/ethtool/cmis_cdb.c:3:
In file included from ./include/linux/ethtool.h:16:
In file included from ./include/linux/bitmap.h:12:
In file included from ./include/linux/string.h:295:
./include/linux/fortify-string.h:579:4: error: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
579 | __write_overflow_field(p_size_field, size);
| ^
./include/linux/fortify-string.h:579:4: error: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
./include/linux/fortify-string.h:579:4: error: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror,-Wattribute-warning]
> + if (err < 0)
> + goto out;
> +
> + offset = CMIS_CDB_CMD_ID_OFFSET +
> + offsetof(struct ethtool_cmis_cdb_request, id);
> + err = __ethtool_cmis_cdb_execute_cmd(dev, &page_data, offset,
> + sizeof(args->req.id),
> + &args->req.id);
> + if (err < 0)
> + goto out;
> +
> + err = cmis_cdb_wait_for_completion(dev, args);
> + if (err < 0)
> + goto out;
> +
> + err = cmis_cdb_wait_for_status(dev, args);
> + if (err < 0)
> + goto out;
> +
> + err = cmis_cdb_process_reply(dev, &page_data, args);
> +
> +out:
> + ethtool_cmis_page_fini(&page_data);
> + return err;
> +}
...
