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lib/vector/vlib: Fix possible null pointer dereference #4638

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lib/vector/vlib: Fix possible null pointer dereference #4638

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17 changes: 10 additions & 7 deletions lib/vector/Vlib/cats.c
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Original file line number Diff line number Diff line change
Expand Up @@ -493,7 +493,7 @@ int Vect_cat_list_to_array(const struct cat_list *list, int **vals, int *nvals)

G_debug(1, "Vect_cat_list_to_array()");

*nvals = n_cats = 0;
*nvals = n_cats = n_ucats = 0;
cats = NULL;
for (i = 0; i < list->n_ranges; i++) {
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It seems to me to be a better solution to make an early exit before this for statement, with something like:

if (list->n_ranges <= 0)
    return -1;

If list->n_ranges is 0 or less, cats and n_cats are never set... and the rest doesn't make any sense.

@metzm Perhaps you may have some insight in this?

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@ymdatta ymdatta Dec 11, 2024 •
edited
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@nilason : Thanks for the review.

But, I am worried that '-1' indicates that something has gone wrong while converting using Vect_cat_list_to_array function, but here there is nothing wrong and it's just that the argument has no elements in it. What do you think about it?

n = list->max[i] - list->min[i] + 1;
Expand All @@ -509,13 +509,16 @@ int Vect_cat_list_to_array(const struct cat_list *list, int **vals, int *nvals)
n_cats += n;
}

/* sort array */
qsort(cats, n_cats, sizeof(int), cmp);
if (cats) {
/* sort array */
qsort(cats, n_cats, sizeof(int), cmp);

/* skip duplicated values */
ucats = G_malloc(sizeof(int) * n_cats);
last_cat = ucats[0] = cats[0];
n_ucats = 1;
}

/* skip duplicated values */
ucats = G_malloc(sizeof(int) * n_cats);
last_cat = ucats[0] = cats[0];
n_ucats = 1;
for (i = 1; i < n_cats; i++) {
if (last_cat == cats[i])
continue;
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