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Zend: prevent malloc(0) in tracked allocator #24495

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Zend: prevent malloc(0) in tracked allocator #24495

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15 changes: 15 additions & 0 deletions Zend/tests/zend_alloc_zero_size.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,15 @@
--TEST--
Zero-size allocations with the tracked allocator
--EXTENSIONS--
zend_test
--ENV--
USE_ZEND_ALLOC=0
USE_TRACKED_ALLOC=1
--FILE--
<?php
var_dump(pack(""));
var_dump(vsprintf("", []));
?>
--EXPECT--
string(0) ""
string(0) ""
4 changes: 4 additions & 0 deletions Zend/zend_alloc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3291,6 +3291,10 @@ static zend_always_inline zend_result tracked_check_max_allocs(zend_mm_heap *hea
static void *tracked_malloc(size_t size ZEND_FILE_LINE_DC ZEND_FILE_LINE_ORIG_DC)
{
zend_mm_heap *heap = AG(mm_heap);

/* malloc(0) may return NULL, so allocate at least one byte. */
size = MAX(size, 1);

if (UNEXPECTED(tracked_check_limit(heap, size ZEND_FILE_LINE_CC) == FAILURE)) {
return NULL;
}
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