re: platform/x86: Add Intel Software Defined Silicon driver

["Colin King (gmail)" <colin.i.king@xxxxxxxxx>]

Hi,

Static analysis with clang scan has detected a potential issue in the 
following commit:

commit 2546c60004309ede8e2d1d5341e0decd90e057bf
Author: David E. Box <david.e.box@xxxxxxxxxxxxxxx>
Date:   Fri Feb 11 17:32:50 2022 -0800

    platform/x86: Add Intel Software Defined Silicon driver

The issue is as follows:

static int sdsi_mbox_read(struct sdsi_priv *priv, struct sdsi_mbox_info 
*info, size_t *data_size)
{
        int ret;

        lockdep_assert_held(&priv->mb_lock);

        ret = sdsi_mbox_acquire(priv, info);
        if (ret)
                return ret;

Note: the return above does not assign a value to *data_size


        return sdsi_mbox_cmd_read(priv, info, data_size);
}


static long state_certificate_read(struct file *filp, struct kobject *kobj,
                                   struct bin_attribute *attr, char 
*buf, loff_t off,
                                   size_t count)
{
        struct device *dev = kobj_to_dev(kobj);
        struct sdsi_priv *priv = dev_get_drvdata(dev);
        u64 command = SDSI_CMD_READ_STATE;
        struct sdsi_mbox_info info;
        size_t size;
               ^
Note: size is not initialized

        int ret;

        if (!priv->sdsi_enabled)
                return -EPERM;

        if (off)
                return 0;

        /* Buffer for return data */
        info.buffer = kmalloc(SDSI_SIZE_READ_MSG, GFP_KERNEL);
        if (!info.buffer)
                return -ENOMEM;

        info.payload = &command;
        info.size = sizeof(command);

        ret = mutex_lock_interruptible(&priv->mb_lock);
        if (ret)
                goto free_buffer;
        ret = sdsi_mbox_read(priv, &info, &size);

Note: a failure in scsi_mbox_read can lead to variable size not being 
assigned a value.

        mutex_unlock(&priv->mb_lock);
        if (ret < 0)
                goto free_buffer;

Note: failure with ret < 0 going to free_buffer

        if (size > count)
                size = count;

        memcpy(buf, info.buffer, size);

free_buffer:
        kfree(info.buffer);

        if (ret)
                return ret;

        return size;

Note: uninitialized value in size being returned. This is an error.

}