


Q: Given the following code slice:
```
1 CLEAR_CONTEXT *clear_context_new(BOOL Compressor)
2 {
3     CLEAR_CONTEXT *clear;
4     clear = (CLEAR_CONTEXT *)calloc(1, sizeof(CLEAR_CONTEXT));
5     if (clear)
6     {
7         clear->Compressor = Compressor;
8         clear->nsc = nsc_context_new();
9         if (!clear->nsc)
10         {
11             return NULL;
12         }
13         nsc_context_set_pixel_format(clear->nsc, RDP_PIXEL_FORMAT_R8G8B8);
14         clear->TempSize = 512 * 512 * 4;
15         clear->TempBuffer = (BYTE *)malloc(clear->TempSize);
16         clear_context_reset(clear);
17     }
18     return clear;
19 }```
which has a CWE-401 vulnerability at line:
```
12         }
```
Please generate the patch for the vulnerability. Please follow the patch format in the exemplars.
To generate this patch, we can follow these reasoning steps:

Step 1. Root Cause Analysis:

1. Function Overview:
   - The function `clear_context_new` allocates memory for a CLEAR_CONTEXT structure and initializes it.

2. Memory Allocation:
   - Line 4: Memory is allocated for the CLEAR_CONTEXT structure using calloc().
   - Line 8: Memory is allocated for the nsc context using nsc_context_new().

3. Error Handling:
   - Line 9-12: If nsc_context_new() fails (returns NULL), the function returns NULL.

4. Vulnerability:
   - The vulnerability occurs because if nsc_context_new() fails, the function returns NULL without freeing the memory allocated for 'clear' on line 4.
   - This results in a memory leak (CWE-401) as the allocated memory becomes inaccessible but is not released.

5. Conclusion:
   - The root cause is improper error handling that fails to clean up resources in the error case.

Step 2. Fixing Strategy:

1. Identify the Resource:
   - The resource that needs to be freed is the 'clear' structure allocated on line 4.

2. Determine the Appropriate Action:
   - Before returning NULL in the error case, we need to free the 'clear' structure.

3. Implement the Fix:
   - Add a call to free(clear) before returning NULL in the error case.

4. Resulting Patch:
```
<         {
<             return NULL;
---
>         {
>             free(clear);
>             return NULL;
```

This patch ensures that if nsc_context_new() fails, the memory allocated for 'clear' is properly freed before the function returns, thus preventing the memory leak.