main: malloc.c:2405: sysmalloc: Assertion `(old_top == initial_top (av) && old_size == 0) || ((unsigned long) (old_size) >= MINSIZE && prev_inuse (old_top) && ((unsigned long) old_end & (pagesize – 1)) == 0)' failed.

When trying to produce a doubly linked list where the user can only add to the head or tail, I end up getting the lovely abortion message at the top.

I have used gdb to narrow it down to what function it is that is causing this, but I really don't know what I'm doing wrong. It allocates the first node, then after that, it throws me the error.
The function is as follows:

data* initD(){
    data *D = NULL;
    D = malloc(sizeof(data*));
    if (!D){
        printf("Error in allocation of data\n");
        exit(0);
    D->head = NULL;
    D->tail = NULL;
    D->next = NULL;
    D->prev = NULL;
    D->val = -1;
    return D; 
You're writing outside of your allocated buffer.
That's because your malloc call passes the wrong size:
D = malloc(sizeof(data*));  // allocate memory for a single pointer
should be:
D = malloc(sizeof(data));  // allocate memory for a whole struct
But really,
D = malloc(sizeof *D);  // allocate memory for whatever D points to
is best because then you don't need to see the declaration of D to check that this line is correct.
Related Solutions
Sysmalloc: Assertion failure on ubuntu environment

Consider using valgrind in such cases - it is very helpful! What it gave to me:
==6454== Invalid write of size 8
==6454==    at 0x4008CE: main (sysmalloc.c:49)
==6454==  Address 0x51e0128 is 0 bytes after a block of size 40 alloc'd
==6454==    at 0x4C2C27B: malloc (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so)
==6454==    by 0x4008B1: main (sysmalloc.c:47)
sysmalloc.c:49 is argv[counter+1] = NULL; - this is line caused problem. Note that in C array indexes start with zero, so for array of length N+1 last index is N. So instead of writing last argv pointer, you wrote NULL to area used internally by sysmalloc and thus caused a fault. 
Change this line to argv[counter] = NULL;
Also note comments about strcpy usage.
    
Malloc error with sysmalloc

I think, you're facing problem in
 my_env[i] = NULL;
This is off-by-one. The maximum index that can be used is
my_env[i-1] = NULL;
Also, please see why not to cast the return value of malloc() and family in C.