Go4Expert - Help please URGENT! creating linked list from tree leaves

hii , I'll appreciate it if someone please help me with this problem
I want to create a linked-list from the leaves of a tree ordered from right to left .
without using a Static or global variable

typedef struct t_node {
int data;
struct t_node *left;
struct t_node *right;
} T_NODE;

typedef struct list_node
{
int data;
struct list_node *next;
} L_NODE;

the function header : L_NODE* leavesRightToLeft (T_NODE* root, 1 more variable )
for example :

Code:

and the function will return a pointer to linked list that will be as following :
1 -> 7 -> 4

I've tried to solve it but i have a problem with the pointers, the idea works, but can you help me with the pointers please
or you can just give me another solution ?

Code:

Lnode *leavesRightToLeft(Tree *root,Lnode *last)

{

        Lnode *p,*p2,*lastleft,*lastright;

        if ( ( root->left==NULL) && (root->right==NULL) )

        {

                p= (Lnode*) malloc (sizeof(Lnode));

                p->next=NULL;

                p->data=root->value;

                last=p;

                return p;

        }

        else if ( !root->left )

        {

                return leavesRightToLeft(root->right,last);

        }

        else if ( !root->right )

        {

                return leavesRightToLeft(root->left,last);

        }    

        else

        {

                p=leavesRightToLeft(root->right,lastright);

                p2=leavesRightToLeft(root->left,lastleft);

                lastright->next=p2;

                last=lastleft;

                return p;

        }

}

Thanks in advanced.