To generate this patch, we can follow these reasoning steps:

Step 1. Root Cause Analysis:

1. Identify the vulnerability:
   - The code has a CWE-476 (NULL Pointer Dereference) vulnerability at line 17.
   - This occurs when `memcpy` is called with `cur->mac_addr` as the destination.

2. Analyze the code flow:
   - `cur` is allocated using `kzalloc` on line 16.
   - Immediately after allocation, `memcpy` is called using `cur`.

3. Identify the issue:
   - `kzalloc` can return NULL if memory allocation fails.
   - There's no check to ensure `cur` is not NULL before using it in `memcpy`.
   - If `cur` is NULL, dereferencing it in `memcpy` will cause a NULL pointer dereference.

Step 2. Fixing Strategy:

1. Add a NULL check:
   - After allocating `cur`, we need to check if the allocation was successful.
   - If `cur` is NULL, we should avoid using it and handle the error condition.

2. Error handling:
   - In case of allocation failure, we should break out of the current loop or function.
   - This prevents the NULL pointer dereference and allows the program to continue execution.

3. Implement the fix:
   - Insert a NULL check immediately after the `kzalloc` call.
   - If `cur` is NULL, break out of the current loop or function.
   - Only proceed with `memcpy` if `cur` is not NULL.

Based on these steps, the generated patch adds a NULL check after memory allocation and breaks the loop if allocation fails, preventing the NULL pointer dereference.