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GSCArray: fix out-of-bounds access in GSCArrayQuickSort #47

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GSCArray: fix out-of-bounds access in GSCArrayQuickSort #47

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5517009
GSCArray: fix out-of-bounds access in GSCArrayQuickSort
DTW-Thalion Jun 28, 2026
f457ca8
GSCArray: address review feedback on the sort test
DTW-Thalion Jul 1, 2026
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6 changes: 6 additions & 0 deletions ChangeLog
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Original file line number Diff line number Diff line change
@@ -1,3 +1,9 @@
2026-06-28 Todd White <todd.white@thalion.global>
* Source/GSCArray.c (GSCArrayQuickSort): Pass the correct partition
lengths to the recursive calls; the right partition length was one
too large, reading one element past the end of the array.
* Tests/CFArray/mutablearray.m: Regression test sorting >16 values.

2021-09-30 Frederik Seiffert <frederik@algoriddim.com>
* Source/CFDate.c: Fix logic in CFGregorianDateIsValid()

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4 changes: 2 additions & 2 deletions Source/GSCArray.c
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Expand Up @@ -58,8 +58,8 @@ GSCArrayQuickSort (const void **array, CFIndex length,
}
GS_EXCHANGE_VALUES (array[stored], array[length - 1]);

GSCArrayQuickSort (array, stored - 1, comparator, context);
GSCArrayQuickSort (array + stored + 1, length - stored, comparator,
GSCArrayQuickSort (array, stored, comparator, context);
GSCArrayQuickSort (array + stored + 1, length - stored - 1, comparator,
context);
}
GSCArrayInsertionSort (array, length, comparator, context);
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46 changes: 45 additions & 1 deletion Tests/CFArray/mutablearray.m
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@@ -1,6 +1,7 @@
#include "CoreFoundation/CFArray.h"
#include "../CFTesting.h"
#include <string.h>
#include <stdlib.h>

#define ARRAY_SIZE 5
const CFIndex array[ARRAY_SIZE] = { 5, 2, 3, 4, 1 };
Expand Down Expand Up @@ -41,7 +42,50 @@ int main (void)

n = CFArrayBSearchValues (ma, CFRangeMake(0, len), (const void*)6, comp, NULL);
PASS_CF(n == 5, "Index of value between values is %d.", (int)n);


{

@HendrikHuebner HendrikHuebner Jul 1, 2026

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Let's use a randomly shuffled range [0; n] as the test input data, and test for a few different values of n.

@DTW-Thalion DTW-Thalion Jul 1, 2026

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Done in f457ca8. The test now sorts a fixed-seed Fisher–Yates shuffle of a contiguous range for sizes 1,2,5,15,16,17,33,64,100 (straddling the insertion-sort/quicksort threshold) and asserts the exact ascending result each time.

One note: I build the input via a pre-sized mutable copy instead of incremental appends, because growing a mutable CFArray across its capacity boundary trips a separate out-of-bounds write in CFArrayCheckCapacityAndGrow/CFArrayReplaceValues (unrelated to this fix). Happy to file that separately.

@DTW-Thalion DTW-Thalion Jul 1, 2026

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Correction on the note above: that CFArray grow-path overflow is not unreported — it is already fixed in #45 (recompute the destination pointer after CFArrayCheckCapacityAndGrow reallocs, and grow to at least the requested capacity). I re-root-caused it here (use-after-realloc write in CFArrayReplaceValues) and confirmed #45 resolves it under ASan. This test just pre-sizes to keep the two PRs independent.

@stefanbidi stefanbidi Jul 3, 2026

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Does the test pass on CoreFoundation on MacOS?

@DTW-Thalion DTW-Thalion Jul 3, 2026

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Someone else will have to test - I have no access to Mac hardware.

/* Sort a shuffled permutation of 1..sz for a range of sizes that straddle
the 16-element threshold between the insertion sort and the quicksort
path (the latter used to read one element past the end of the array).
The sorted result must be exactly 1, 2, ..., sz. */
const CFIndex sizes[] = { 1, 2, 5, 15, 16, 17, 33, 64, 100 };
const void *shuf[100];
CFIndex s;

srand (1);
for (s = 0; s < (CFIndex)(sizeof(sizes) / sizeof(sizes[0])); s++)
{
CFIndex sz = sizes[s];
CFArrayRef src;
CFMutableArrayRef big;
Boolean ordered = true;
CFIndex i;

for (i = 0; i < sz; i++)
shuf[i] = (const void *)(CFIndex)(i + 1);
for (i = sz - 1; i > 0; i--)
{
CFIndex j = rand () % (i + 1);
const void *t = shuf[i];
shuf[i] = shuf[j];
shuf[j] = t;
}

src = CFArrayCreate (NULL, shuf, sz, NULL);
big = CFArrayCreateMutableCopy (NULL, sz, src);
CFArraySortValues (big, CFRangeMake (0, sz), comp, NULL);

for (i = 0; i < sz; i++)
if ((CFIndex) CFArrayGetValueAtIndex (big, i) != i + 1)
ordered = false;

PASS_CF(ordered && CFArrayGetCount (big) == sz,
"Shuffled range of %d values sorts to ascending order.", (int)sz);
CFRelease (big);
CFRelease (src);
}
}

return 0;
}