C - Writing a struct into a 2D array causes Segmentation Fault - arrays

Question

I'm trying to write a program that reads a text file into a 2D array of structs, but trying to put a struct into that array causes the program to crash.
Here's the program
ppm.c
#include "ppm.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
image parse_ascii_image(FILE *fp) {
char magic[3];
char comm[1024];
char size[10];
image img;
int height;
int width;
... // some code
pixel **pixelarr;
printf("Commencing internal malloc...\n");
if (height <= 1024 && width <= 1024 && height > 0 && width > 0){
pixelarr = (pixel **) malloc(height * sizeof(pixel*));
}else{
fprintf(stderr, "Error: Invalid image size: %d * %d", width, height);
return img;
}
for (int i = 0; i < height; i++){
pixelarr[i] = malloc(width * sizeof(pixel));
}
int d = 0;
int e;
printf("Filling in array:\n");
for (int row = 0; row < height; row++){
for (int col = 0; col < width; col++){
for (int i = 0; i < 3; i++){
while ((e = fgetc(fp)) != '\n'){
d = d * 10;
e = e - 60;
d += e;
}
if (i == 0){
pixelarr[row][col].red = d;
}
if (i == 1){
pixelarr[row][col].green = d;
}
if (i == 2){
pixelarr[row][col].blue = d;
}
d = 0;
}
}
}
printf("Finished! Copying pixels over: \n");
for (int row = 0; row < height; row++){
for (int col = 0; col < width; col++){
img.pixels[row][col] = pixelarr[row][col];
// ^^^This is where the program crashes
}
}
printf("Finished! Freeing internal malloc:\n");
... // some more code
}
relevant info from ppm.h:
#ifndef PPM_H
#define PPM_H 1
#include <stdio.h>
...
typedef struct pixel pixel;
struct pixel {
int red;
int green;
int blue;
};
typedef struct image image;
struct image {
enum ppm_magic magic; // PPM format
char comments[1024]; // All comments truncated to 1023 characters
int width; // image width
int height; // image height
int max_color; // maximum color value
pixel **pixels; // 2D array of pixel structs.
};
...
// Parses an ASCII PPM file.
image parse_ascii_image(FILE *fp);
...
#endif
If anyone can help me figure out what's causing my program to crash there, I would appreciate it.
Thank you!

Answer 1

A few problems:
1: img.pixels is never initialized. Anytime you create a pointer to something without assigning it a value first, try to set it to NULL so it's easier to debug. Note that this will not fix the issue. To fix it, simply initialize them with a struct instance.
2: You should free pixelarr. Most modern OS's do this, but it's still really, really good practice.
3: Wouldn't it be easier to not use the nested loops, and instead do img.pixels = pixelarr? It achieves the same (unless this is for a class, and this part is required).