C, Why Is Valgrind Showing Errors Detected For This Code?

I’m trying to submit code that is auto graded for uni, and I fail the last test case checking for memory being cleared and other errors. I have been looking at my code for hours and have no idea why it outputs errors

in use at exit: 0 bytes in 0 blocks
ERROR SUMMARY: 11 errors from 3 contexts (suppressed: 0 from 0)

This code is supposed to take either a file or stdin, and print out each line in reverse. It does that correctly without crashing. It even passes all the functional test cases.

#define _DEFAULT_SOURCE
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>


int main(int argc, char ** argv){
    FILE* file;
    if(argc>1){
        file = fopen(argv[1],"r");
    }
    else{
        file=stdin;
    }
    //FILE* file = fopen(argv[1],"r");
    //if(!(file))file=stdin;

    
    int len=0;
    char **array = malloc(sizeof(char*));
    array[len] = malloc(sizeof(char)*255);
    
    while(!(feof(file))){               
        fgets(array[len],255,file);
        len++;
        array = realloc(array,sizeof(char*)*(len+1));
        array[len] = malloc(sizeof(char)*255);
    }
    

    for(int i=len;i>=0;i--){
        printf("%s",array[i]);
    }
    
    for(int i=0; i<=len; i++){
        free(array[i]);
    }
    
    fclose(file);
    free(array);
    
    return 0;
}

Any help would be appreciated thanks!

>Solution :

You are not null terminating the last line

while (!(feof(file))) {
    fgets(array[len], 255, file);
    len++;
    array = realloc(array, sizeof(char*) * (len + 1));
    array[len] = malloc(sizeof(char) * 255);
    *array[len] = 0; <<<<==========
   }

This at least produces good output now, dont knwo if valgrind complains or not because I am not on linux.