Step 1:  code snippet provided does not directly show a CWE-476 (NULL Pointer Dereference) vulnerability in the line:
```
6 	char *sm_alternate = NULL, *error_strategy = NULL;
```
However, to reason about how a NULL pointer dereference vulnerability could occur, we need to consider the subsequent use of these pointers in the function `clone_submodule`. The vulnerability would typically manifest if these pointers are dereferenced without proper checks to ensure they are not NULL. Here’s a step-by-step analysis:

### Step 1: Initialization of Pointers
- The pointers `sm_alternate` and `error_strategy` are initialized to NULL.
- Initializing pointers to NULL is a common practice to ensure they are not pointing to arbitrary memory locations.

### Step 2: Potential Use of Pointers
- Since the actual usage of these pointers is not shown in the snippet, we must hypothesize based on common practices.
- These pointers might be intended to store addresses of strings or other data structures. If the function `clone_submodule` attempts to use these pointers (e.g., accessing data through them or passing them to other functions expecting valid addresses), it must first ensure they point to valid memory.

### Step 3: Hypothetical Vulnerable Behavior
- If `clone_submodule` or any function it calls tries to dereference `sm_alternate` or `error_strategy` without first checking if they are not NULL, it would lead to a NULL pointer dereference. For example:
  ```c
  if (strcmp(sm_alternate, "some_value") == 0) {
      // do something
  }
  ```
- In the above hypothetical code, if `sm_alternate` is still NULL when `strcmp` is called, it would cause a NULL pointer dereference because `strcmp` expects valid C-string pointers.

### Step 4: Ensuring Safety
- To prevent a NULL pointer dereference, the function should include checks before dereferencing these pointers:
  ```c
  if (sm_alternate != NULL && strcmp(sm_alternate, "some_value") == 0) {
      // do something
  }
  ```
- Additionally, the function might need to allocate memory or ensure that these pointers are assigned to valid addresses before any dereferencing occurs.

### Conclusion:
The vulnerability (CWE-476) would occur if there is an attempt to dereference `sm_alternate` or `error_strategy` without verifying that they have been assigned non-NULL values after their initialization. Proper checks should be implemented to ensure these pointers are valid before any operations that require dereferencing. The provided code snippet does not show the actual dereferencing, so the analysis assumes typical scenarios where such vulnerabilities might occur.
Based on the hypothetical scenarios where `sm_alternate` and `error_strategy` could be dereferenced without proper checks, here are five possible patches to address the potential CWE-476 vulnerability:

### Patch 1: Check before Dereferencing
```diff
+ if (sm_alternate != NULL) {
    // Code that dereferences sm_alternate
+ }
```

### Patch 2: Initialize with Valid Memory
```diff
- char *sm_alternate = NULL, *error_strategy = NULL;
+ char *sm_alternate = malloc(INITIAL_SIZE), *error_strategy = malloc(INITIAL_SIZE);
+ if (sm_alternate == NULL || error_strategy == NULL) {
+     // Handle memory allocation failure
+ }
```

### Patch 3: Assign Default Values
```diff
- char *sm_alternate = NULL, *error_strategy = NULL;
+ char sm_alternate_default[] = "default_value";
+ char error_strategy_default[] = "default_strategy";
+ char *sm_alternate = sm_alternate_default, *error_strategy = error_strategy_default;
```

### Patch 4: Parameter Validation
```diff
+ // Assuming clone_submodule is called with sm_alternate and error_strategy as parameters
+ if (sm_alternate == NULL || error_strategy == NULL) {
+     // Handle NULL parameters
+ }
```

### Patch 5: Safe Function Wrappers
```diff
+ // Assuming a hypothetical function that safely compares strings
+ if (safe_strcmp(sm_alternate, "some_value") == 0) {
    // do something
+ }
```
In the `safe_strcmp` function, you would implement the necessary NULL checks before calling `strcmp`.

Each of these patches addresses the potential for a NULL pointer dereference in different ways, depending on the context of how `sm_alternate` and `error_strategy` are used within the `clone_submodule` function and the broader codebase. It's important to choose a patch strategy that aligns with the specific use case and coding standards of the project.