Based on the provided code slice and the specified vulnerability (CWE-476: NULL Pointer Dereference) on line 5, here are five possible patches to address the issue:

Patch 1:
```c
if (!partner || !partner->dev) {
    return ERR_PTR(-EINVAL);
}
return typec_register_altmode(&partner->dev, desc);
```

Patch 2:
```c
struct typec_altmode *altmode;
if (!partner) {
    return ERR_PTR(-EINVAL);
}
altmode = typec_register_altmode(&partner->dev, desc);
return altmode ? altmode : ERR_PTR(-ENODEV);
```

Patch 3:
```c
if (!partner) {
    pr_err("Invalid partner pointer\n");
    return NULL;
}
return typec_register_altmode(&partner->dev, desc);
```

Patch 4:
```c
struct typec_altmode *altmode = NULL;
if (partner && partner->dev) {
    altmode = typec_register_altmode(&partner->dev, desc);
}
return altmode ? altmode : ERR_PTR(-EINVAL);
```

Patch 5:
```c
return partner ? typec_register_altmode(&partner->dev, desc) : ERR_PTR(-ENODEV);
```

Each of these patches aims to check for NULL pointers before dereferencing them, either returning an error or handling the case appropriately. The choice of patch depends on the specific requirements of the surrounding code and error handling conventions in the project.