To generate the patch for the CWE-401 (Memory Leak) vulnerability in the given code slice, we need to follow a systematic approach to identify the root cause of the vulnerability and then apply an appropriate fix. Here are the detailed reasoning steps:

### Step 1: Root Cause Analysis

1. **Understanding the Code Context:**
   - The function `ff_rtsp_close_streams` is responsible for closing and cleaning up RTSP streams associated with an `AVFormatContext` object.
   - The function iterates over the `rtsp_streams` array, performs some cleanup operations, and then frees various resources.

2. **Identifying the Vulnerability:**
   - The loop at lines 7-17 iterates over the `rtsp_streams` array and performs cleanup operations for each stream.
   - The `if` conditions at lines 10 and 12 check if the `rtsp_st` pointer and its `dynamic_handler` and `dynamic_protocol_context` members are valid before calling the `close` method.
   - However, after performing the cleanup operations, the memory allocated for each `RTSPStream` object (`rtsp_st`) is not freed.

3. **Memory Leak Identification:**
   - The `RTSPStream` objects are dynamically allocated, and their pointers are stored in the `rt->rtsp_streams` array.
   - Failing to free these objects results in a memory leak, as the allocated memory is not reclaimed even after the streams are closed.

### Step 2: Fixing Strategy

1. **Freeing the Allocated Memory:**
   - To fix the memory leak, we need to ensure that the memory allocated for each `RTSPStream` object is freed after it is no longer needed.
   - This can be done by calling `av_free(rtsp_st)` after the cleanup operations within the loop.

2. **Applying the Patch:**
   - The patch should add a call to `av_free(rtsp_st)` after the `if` block that performs the cleanup operations.
   - This ensures that each `RTSPStream` object is properly freed, preventing the memory leak.

### Conclusion

The patch should be applied as follows:

```diff
<             }
<         }
---
>             }
>             av_free(rtsp_st);
>         }
```

### Final Code with Patch Applied

```c
1 void ff_rtsp_close_streams(AVFormatContext *s)
2 {
3     RTSPState *rt = s->priv_data;
4     int i;
5     RTSPStream *rtsp_st;
6     ff_rtsp_undo_setup(s);
7     for (i = 0; i < rt->nb_rtsp_streams; i++)
8     {
9         rtsp_st = rt->rtsp_streams[i];
10         if (rtsp_st)
11         {
12             if (rtsp_st->dynamic_handler && rtsp_st->dynamic_protocol_context)
13             {
14                 rtsp_st->dynamic_handler->close(rtsp_st->dynamic_protocol_context);
15             }
16             av_free(rtsp_st);
17         }
18     }
19     av_free(rt->rtsp_streams);
20     if (rt->asf_ctx)
21     {
22         av_close_input_stream(rt->asf_ctx);
23         rt->asf_ctx = NULL;
24     }
25     av_free(rt->p);
26     av_free(rt->recvbuf);
27 }
```

By adding the `av_free(rtsp_st);` call within the loop, we ensure that each `RTSPStream` object is properly freed, thus preventing the memory leak and addressing the CWE-401 vulnerability.