Based on the provided code slice and the identified vulnerability (CWE-787: Out-of-bounds Write) in line 6, here are five possible patches to address the issue:

Patch 1: Add size validation
```c
6 	size_t size = NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
7 			nla_total_size(1) + nla_total_size(4);
8 	if (size > MAX_SAFE_SIZE) {
9 		err = -EINVAL;
10 		goto errout;
11 	}
12 	skb = nlmsg_new(size, GFP_KERNEL);
```

Patch 2: Use a safer allocation function
```c
6 	skb = nlmsg_new_safe(NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
7 			nla_total_size(1) + nla_total_size(4), GFP_KERNEL);
```

Patch 3: Implement bounds checking
```c
6 	size_t msg_size = sizeof(struct ifaddrmsg);
7 	size_t total_size = NLMSG_ALIGN(msg_size) +
8 			nla_total_size(1) + nla_total_size(4);
9 	if (total_size < msg_size) {
10 		err = -EINVAL;
11 		goto errout;
12 	}
13 	skb = nlmsg_new(total_size, GFP_KERNEL);
```

Patch 4: Use a constant maximum size
```c
6 	#define MAX_SKB_SIZE 1024
7 	size_t size = min_t(size_t, NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
8 			nla_total_size(1) + nla_total_size(4), MAX_SKB_SIZE);
9 	skb = nlmsg_new(size, GFP_KERNEL);
```

Patch 5: Implement overflow detection
```c
6 	size_t base_size = NLMSG_ALIGN(sizeof(struct ifaddrmsg));
7 	size_t extra_size = nla_total_size(1) + nla_total_size(4);
8 	if (base_size > SIZE_MAX - extra_size) {
9 		err = -EINVAL;
10 		goto errout;
11 	}
12 	skb = nlmsg_new(base_size + extra_size, GFP_KERNEL);
```