Thank you for providing the code snippet and identifying the vulnerability. To address the CWE-787 (Out-of-bounds Write) vulnerability in the `skb_put(n, skb->len)` line, here are five possible patches:

Patch 1: Add a size check before calling skb_put
```c
if (skb->len <= skb_tailroom(n)) {
    skb_put(n, skb->len);
} else {
    kfree_skb(n);
    return NULL;
}
```

Patch 2: Use skb_put_data instead of skb_put
```c
if (skb_put_data(n, skb->data, skb->len) < 0) {
    kfree_skb(n);
    return NULL;
}
```

Patch 3: Implement a custom safe_skb_put function
```c
static inline void *safe_skb_put(struct sk_buff *skb, unsigned int len)
{
    if (len > skb_tailroom(skb))
        return NULL;
    return skb_put(skb, len);
}

// Then use it in the function
if (!safe_skb_put(n, skb->len)) {
    kfree_skb(n);
    return NULL;
}
```

Patch 4: Use skb_put_padto to ensure sufficient space
```c
if (skb_put_padto(n, skb->len) < 0) {
    kfree_skb(n);
    return NULL;
}
```

Patch 5: Check available space and adjust allocation if necessary
```c
if (skb->len > skb_tailroom(n)) {
    kfree_skb(n);
    n = __alloc_skb(newheadroom + skb->len + newtailroom + 16, // Add extra space
                    gfp_mask, skb_alloc_rx_flag(skb),
                    NUMA_NO_NODE);
    if (!n)
        return NULL;
    skb_reserve(n, newheadroom);
}
skb_put(n, skb->len);
```

Each of these patches aims to prevent potential buffer overflow by ensuring that there's enough space in the destination buffer before writing data.