Re: [PATCH v5 4/9] cxl/mem: Add basic IOCTL interface

Konrad Rzeszutek Wilk
2021-02-20T01:24:27Z

..snip..
> +static int handle_mailbox_cmd_from_user(struct cxl_mem *cxlm,
> + const struct cxl_mem_command *cmd,
> + u64 in_payload, u64 out_payload,
> + s32 *size_out, u32 *retval)
> +{
> + struct device *dev = &cxlm->pdev->dev;
> + struct mbox_cmd mbox_cmd = {
> + .opcode = cmd->opcode,
> + .size_in = cmd->info.size_in,
> + .size_out = cmd->info.size_out,
> + };
> + int rc;
> +
> + if (cmd->info.size_out) {
> + mbox_cmd.payload_out = kvzalloc(cmd->info.size_out, GFP_KERNEL);
> + if (!mbox_cmd.payload_out)
> + return -ENOMEM;
> + }
> +
> + if (cmd->info.size_in) {
> + mbox_cmd.payload_in = vmemdup_user(u64_to_user_ptr(in_payload),
> + cmd->info.size_in);
> + if (IS_ERR(mbox_cmd.payload_in))
> + return PTR_ERR(mbox_cmd.payload_in);

Not that this should happen, but what if info.size_out was set? Should
you also free mbox_cmd.payload_out?

> + }
> +
> + rc = cxl_mem_mbox_get(cxlm);
> + if (rc)
> + goto out;
> +
> + dev_dbg(dev,
> + "Submitting %s command for user\n"
> + "\topcode: %x\n"
> + "\tsize: %ub\n",
> + cxl_command_names[cmd->info.id].name, mbox_cmd.opcode,
> + cmd->info.size_in);
> +
> + rc = __cxl_mem_mbox_send_cmd(cxlm, &mbox_cmd);
> + cxl_mem_mbox_put(cxlm);
> + if (rc)
> + goto out;
> +
> + /*
> + * @size_out contains the max size that's allowed to be written back out
> + * to userspace. While the payload may have written more output than
> + * this it will have to be ignored.
> + */
> + if (mbox_cmd.size_out) {
> + dev_WARN_ONCE(dev, mbox_cmd.size_out > *size_out,
> + "Invalid return size\n");
> + if (copy_to_user(u64_to_user_ptr(out_payload),
> + mbox_cmd.payload_out, mbox_cmd.size_out)) {
> + rc = -EFAULT;
> + goto out;
> + }
> + }
> +
> + *size_out = mbox_cmd.size_out;
> + *retval = mbox_cmd.return_code;
> +
> +out:
> + kvfree(mbox_cmd.payload_in);
> + kvfree(mbox_cmd.payload_out);
> + return rc;
> +}

..snip..

> +static int cxl_query_cmd(struct cxl_memdev *cxlmd,
> + struct cxl_mem_query_commands __user *q)
> +{
> + struct device *dev = &cxlmd->dev;
> + struct cxl_mem_command *cmd;
> + u32 n_commands;
> + int j = 0;

How come it is 'j' instead of the usual 'i'?
> +
> + dev_dbg(dev, "Query IOCTL\n");
> +
> + if (get_user(n_commands, &q->n_commands))
> + return -EFAULT;
> +
> + /* returns the total number if 0 elements are requested. */
> + if (n_commands == 0)
> + return put_user(cxl_cmd_count, &q->n_commands);
> +
> + /*
> + * otherwise, return max(n_commands, total commands) cxl_command_info
> + * structures.
> + */
> + cxl_for_each_cmd(cmd) {
> + const struct cxl_command_info *info = &cmd->info;
> +
> + if (copy_to_user(&q->commands[j++], info, sizeof(*info)))
> + return -EFAULT;
> +
> + if (j == n_commands)
> + break;
> + }
> +
> + return 0;
> +}
> +