while loop to build up a list not ending - c

Question

I'm trying to figure out why my code isn't working but i haven't managed so far. The code should analyse a string and build up a list containing all which letters from the english alphabet (contained in alf) are contained in that string (*s) and how many times:
` char c, *s, alf[26]={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'};
the string is then acquired from a file and i've got no problem until there, i've managed to print it out correctly on the prompt so that's working. Anyway here's what i did(int variables d and num will be used later):
FILE *f=fopen("prova.txt","r");
int d,l=0,num;
while(feof(f)==0){
l++;
fscanf(f,"%c",&c);
}
s=malloc(sizeof(l*sizeof(char)));
rewind(f);
l=0;
while(feof(f)==0){
fscanf(f,"%c",s+l);
l++;
}
//"stringa acquisita" stands for "acquired string"
printf("\nstringa acquisita:%s",s);
And the string gets printed out correctly, excepting from the fact that it gets one charachter more than it should. Any advices in that direction are also welcome.
So i got to building the list. Here's what I did:
typedef struct Nodo{char car; int rip; struct Nodo* next;} Nodo;
typedef Nodo* lista;
lista head = NULL, el, temp;
for(l=0;l<26;l++){
num=0;
for(d=0;d<strlen(s);d++){
if(s[d]==alf[l]){
num++;
}
}
if(num!=0){
el = malloc(sizeof(Nodo));
if(el==NULL){
perror("error malloc\n");
exit(1);
}
el->car=alf[l];
el->rip=num;
if(head==NULL){
head=el;
el->next=NULL;
//this printf doesn't print anything on the prompt
printf("\n%c\n%d", head->car,head->rip);
}
else{
temp=head;
while(temp->next!=NULL){
temp=temp->next;
}
temp->next=el;
el->next=NULL;
}
}
//this printf prints only one time
printf("CHECKIT\n");
}
And here my code crashes. As i specified in the comments, I put two printf to get to see what's going on. The first one doesn't give anything printed on the prompt, about the second one i get one "CHECKIT" printed out and then everything crashes. Can anyone tell me what I'm missing here?
Thank you a lot.
/EDIT/
There was one sizeof more than it should have been:`
s=malloc(sizeof(l*sizeof(char)));` `
Corrected that with
s=malloc(l*sizeof(char));
everything works correctly.
Thanks everyone.