Based on the provided code slice and the specified vulnerability types (CWE-787: Out-of-bounds Write and CWE-125: Out-of-bounds Read) between lines 14 and 24, the main issue appears to be potential buffer overflow when reading user input into user_val. Here are five possible patches to address this vulnerability:

Patch 1: Limit the input size in memdup_user and add bounds checking for sscanf
```
14 	cmd_buf = memdup_user(buf, min_t(size_t, count, sizeof(user_val) - 1));
...
24 	cnt = sscanf(cmd_buf, "%15s", user_val);
```

Patch 2: Use strncpy with explicit null termination
```
14 	cmd_buf = memdup_user(buf, count);
...
24 	strncpy(user_val, cmd_buf, sizeof(user_val) - 1);
25 	user_val[sizeof(user_val) - 1] = '\0';
26 	cnt = 1;
```

Patch 3: Use strlcpy for safer string copying
```
14 	cmd_buf = memdup_user(buf, count);
...
24 	strlcpy(user_val, cmd_buf, sizeof(user_val));
25 	cnt = 1;
```

Patch 4: Use snprintf with size limit
```
14 	cmd_buf = memdup_user(buf, count);
...
24 	cnt = snprintf(user_val, sizeof(user_val), "%s", cmd_buf);
25 	if (cnt >= sizeof(user_val))
26 		return -EINVAL;
```

Patch 5: Implement custom safe string copy function
```
static inline void safe_strcpy(char *dst, const char *src, size_t size)
{
    size_t i;
    for (i = 0; i < size - 1 && src[i]; i++)
        dst[i] = src[i];
    dst[i] = '\0';
}

...

14 	cmd_buf = memdup_user(buf, count);
...
24 	safe_strcpy(user_val, cmd_buf, sizeof(user_val));
25 	cnt = 1;
```

Each of these patches aims to prevent buffer overflow by ensuring that the user input is properly bounded when copied into the user_val array.