Based on the provided code and the specified vulnerability (CWE-476: NULL Pointer Dereference) on line 8, here are five possible patches:

Patch 1:
```c
if (str == NULL)
{
    SetLastError(ERROR_INVALID_PARAMETER);
    return -1;
}
```

Patch 2:
```c
if (!str)
{
    return 0;
}
```

Patch 3:
```c
if (str == NULL)
{
    return 0;
}
```

Patch 4:
```c
if (!str || len == 0)
{
    return 0;
}
```

Patch 5:
```c
if (str == NULL)
{
    SetLastError(ERROR_INVALID_PARAMETER);
    return 0;
}
```

Each of these patches replaces the WINPR_ASSERT(str) with a proper null check, handling the case where str is NULL. The patches differ in their error handling approach (returning -1, 0, or setting an error code) based on the specific requirements of the function.