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wave16: dart-0001/2/3 + octave-0002 + php-0003/4 + cassandra-0005 + erlang-0003 + chef-0001 — 542/240

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russell@unturf.com 2026-03-27 19:36:35 -04:00
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114
defects/php/patch/php-0003-interface-dedup-hashset.md Normal file
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# php-0003: zend_do_implement_interfaces — O(I²) interface dedup linear scan
## Summary
| Field | Value |
|-------------|-------|
| ID | php-0003 |
| Severity | MEDIUM |
| CWE | CWE-407 (Algorithmic Complexity) |
| File | `Zend/zend_inheritance.c` |
| Function | `zend_do_implement_interfaces` |
| Lines | 2259–2290 |
| Speedup | ~250x op-count at I=500 interfaces |
## Defect
When PHP links a class that implements I interfaces (including inherited ones),
`zend_do_implement_interfaces` builds a deduplicated `interfaces[]` array.
For each new interface, it scans the already-accumulated array linearly:
```c
// zend_inheritance.c:2259
for (i = 0; i < ce->num_interfaces; i++) {
zend_class_entry *iface = interfaces[num_parent_interfaces + i];
// ...
for (uint32_t j = 0; j < num_interfaces; j++) { // O(num_interfaces)
if (interfaces[j] == iface) { // pointer equality
// skip duplicate
...
break;
}
}
if (iface) {
interfaces[num_interfaces] = iface;
num_interfaces++;
}
}
```
The outer loop runs `ce->num_interfaces` times.
The inner loop scans up to `num_interfaces` (parent + accumulated so far) each time.
Total: O(P×I + I²) where P = parent interface count, I = new interface count.
In deeply nested interface hierarchies (Symfony, Laravel, Drupal), a class
can implement dozens of transitive interfaces. E.g., a class implementing
5 interfaces where each interface extends 10 others = 50+ total interfaces.
## Root Cause
The `interfaces[]` array is a flat C array with no corresponding hash set.
Duplicate detection uses pointer equality but relies on a linear scan.
## Fix
Use a temporary `HashTable` (or a pointer-keyed hash set) to track which
interface pointers have already been added:
```diff
--- a/Zend/zend_inheritance.c
+++ b/Zend/zend_inheritance.c
@@ -2251,7 +2251,9 @@ static void zend_do_implement_interfaces(...)
{
uint32_t num_parent_interfaces = ce->parent ? ce->parent->num_interfaces : 0;
uint32_t num_interfaces = num_parent_interfaces;
+ HashTable iface_set;
+ zend_hash_init(&iface_set, num_parent_interfaces + ce->num_interfaces, NULL, NULL, 0);
+ /* pre-populate with parent interfaces */
+ for (uint32_t k = 0; k < num_parent_interfaces; k++) {
+ zend_hash_index_add_empty_element(&iface_set, (zend_ulong)(uintptr_t)interfaces[k]);
+ }
for (i = 0; i < ce->num_interfaces; i++) {
zend_class_entry *iface = interfaces[num_parent_interfaces + i];
- /* O(num_interfaces) linear scan for duplicate */
- for (uint32_t j = 0; j < num_interfaces; j++) {
- if (interfaces[j] == iface) {
- /* duplicate found */
- ...
- iface = NULL;
- break;
- }
- }
+ /* O(1) hash lookup for duplicate */
+ if (zend_hash_index_find(&iface_set, (zend_ulong)(uintptr_t)iface) != NULL) {
+ /* duplicate: inherit constants but don't add to interfaces[] */
+ ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&iface->constants_table, key, c) {
+ do_inherit_constant_check(ce, c, key);
+ } ZEND_HASH_FOREACH_END();
+ continue;
+ }
if (iface) {
interfaces[num_interfaces] = iface;
+ zend_hash_index_add_empty_element(&iface_set, (zend_ulong)(uintptr_t)iface);
num_interfaces++;
}
}
+ zend_hash_destroy(&iface_set);
```
## Measurement
Simulated with `PhpInterfaceDedupAlgorithm.java`:
| I | slow ops | fast ops | ratio |
|------|----------|----------|-------|
| 50 | 1,275 | 50 | 25× |
| 200 | 20,100 | 200 | 100× |
| 500 | 125,250 | 500 | 250× |
## References
- `Zend/zend_inheritance.c` lines 2251–2312 (`zend_do_implement_interfaces`)
- `Zend/zend_inheritance.c` lines 2268–2285 (inner dedup loop)
- Related: php-0004 (`zend_do_inherit_interfaces` same pattern)

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# php-0004: zend_do_inherit_interfaces — O(IF × CE) interface inheritance dedup linear scan
## Summary
| Field | Value |
|-------------|-------|
| ID | php-0004 |
| Severity | MEDIUM |
| CWE | CWE-407 (Algorithmic Complexity) |
| File | `Zend/zend_inheritance.c` |
| Function | `zend_do_inherit_interfaces` |
| Lines | 1592–1623 |
| Speedup | ~150x op-count at IF=CE=500 |
## Defect
When a class inherits from a parent or implements an interface, PHP calls
`zend_do_inherit_interfaces` to copy the interface's interface list into the
class's own interface list (without duplicates). For each of IF parent interfaces,
it does an O(CE) linear scan over the class's current `ce_num` interfaces:
```c
// zend_inheritance.c:1606
while (if_num--) {
zend_class_entry *entry = iface->interfaces[if_num];
for (i = 0; i < ce_num; i++) { // O(ce_num) scan
if (ce->interfaces[i] == entry) { // pointer equality
break;
}
}
if (i == ce_num) {
ce->interfaces[ce->num_interfaces++] = entry;
}
}
```
The outer loop is `if_num` = number of interfaces in the implemented interface.
The inner loop scans `ce_num` = current class interface count.
Total: O(IF × CE).
This function is called once per implemented interface during class linking
(`do_interface_implementation` → `zend_do_inherit_interfaces`). A class
implementing K interfaces, each with M sub-interfaces, results in K calls
each costing O(M × K×M) = O(K × M²) overall.
In Symfony/Laravel, deeply nested interface hierarchies (Countable, Traversable,
Iterator, IteratorAggregate, etc.) can produce dozens of inherited interfaces
per class.
## Root Cause
`ce->interfaces` is a flat pointer array. Duplicate detection uses a linear
scan rather than a pointer set.
## Fix
Maintain a pointer hash set that grows as interfaces are added:
```diff
--- a/Zend/zend_inheritance.c
+++ b/Zend/zend_inheritance.c
@@ -1592,6 +1592,9 @@ static void zend_do_inherit_interfaces(...)
{
uint32_t i, ce_num, if_num = iface->num_interfaces;
ce_num = ce->num_interfaces;
+ HashTable iface_set;
+ zend_hash_init(&iface_set, ce_num + if_num, NULL, NULL, 0);
+ for (i = 0; i < ce_num; i++) {
+ zend_hash_index_add_empty_element(&iface_set, (zend_ulong)(uintptr_t)ce->interfaces[i]);
+ }
while (if_num--) {
zend_class_entry *entry = iface->interfaces[if_num];
- for (i = 0; i < ce_num; i++) {
- if (ce->interfaces[i] == entry) {
- break;
- }
- }
- if (i == ce_num) {
+ if (!zend_hash_index_find(&iface_set, (zend_ulong)(uintptr_t)entry)) {
ce->interfaces[ce->num_interfaces++] = entry;
+ zend_hash_index_add_empty_element(&iface_set, (zend_ulong)(uintptr_t)entry);
}
}
+ zend_hash_destroy(&iface_set);
```
## Measurement
Simulated with `PhpInterfaceDedupAlgorithm.java`:
| IF | CE | slow ops | fast ops | ratio |
|------|------|----------|----------|-------|
| 50 | 50 | 2,500 | 100 | 25× |
| 200 | 200 | 40,000 | 400 | 100× |
| 500 | 500 | 250,000 | 1,000 | 250× |
## References
- `Zend/zend_inheritance.c` lines 1592–1623 (`zend_do_inherit_interfaces`)
- `Zend/zend_inheritance.c` lines 1606–1616 (inner dedup loop)
- Related: php-0003 (`zend_do_implement_interfaces` same pattern)

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package unit;
import java.util.HashSet;
import java.util.Set;
/**
* CWE-407 unit test: php-0003 + php-0004
*
* Models PHP's interface dedup during class linking:
* php-0003: zend_do_implement_interfaces (zend_inheritance.c:2259-2290)
* php-0004: zend_do_inherit_interfaces (zend_inheritance.c:1606-1616)
*
* DEFECT (php-0003): When linking a class with I new interfaces, for each
* new interface, a linear scan of all accumulated interfaces checks for
* duplicates. Total: O(P*I + I^2) where P = parent interface count.
*
* DEFECT (php-0004): When inheriting IF interfaces from a parent/iface,
* for each of IF entries, a linear scan of CE existing class interfaces
* checks for duplicates. Total: O(IF * CE).
*
* FIX: use a HashSet of interface pointers (simulated here as integer IDs)
* for O(1) membership test. Total: O(I) or O(IF + CE).
*
* Asserts: slowOps > fastOps * 5 at I=500+ (actual ratio ~250x at I=500).
*/
public class PhpInterfaceDedupAlgorithm {
// --- php-0003: zend_do_implement_interfaces ---
/**
* Simulate zend_do_implement_interfaces defective path.
* For each of numNew new interfaces, scan accumulated array for duplicates.
*
* @param numParent number of interfaces already inherited from parent
* @param numNew number of new interfaces the class declares
* @return total pointer-comparison operations
*/
static long slow0003(int numParent, int numNew) {
// interfaces[] array: first numParent are pre-populated from parent
int[] interfaces = new int[numParent + numNew];
for (int k = 0; k < numParent; k++) {
interfaces[k] = k; // simulated interface pointers as IDs
}
int numInterfaces = numParent;
long ops = 0;
for (int i = 0; i < numNew; i++) {
int iface = numParent + i; // new interface ID
boolean duplicate = false;
// Inner loop: O(numInterfaces) linear scan
for (int j = 0; j < numInterfaces; j++) {
ops++;
if (interfaces[j] == iface) {
duplicate = true;
break;
}
}
if (!duplicate) {
interfaces[numInterfaces] = iface;
numInterfaces++;
}
}
return ops;
}
/**
* Simulate zend_do_implement_interfaces patched path.
* Use HashSet for O(1) membership test.
*
* @param numParent number of parent interfaces
* @param numNew number of new interfaces
* @return total operations
*/
static long fast0003(int numParent, int numNew) {
Set<Integer> ifaceSet = new HashSet<>(numParent + numNew);
long ops = 0;
// Pre-populate from parent — O(numParent)
for (int k = 0; k < numParent; k++) {
ifaceSet.add(k);
ops++;
}
for (int i = 0; i < numNew; i++) {
int iface = numParent + i;
ops++; // O(1) hash probe
if (!ifaceSet.contains(iface)) {
ifaceSet.add(iface);
}
}
return ops;
}
// --- php-0004: zend_do_inherit_interfaces ---
/**
* Simulate zend_do_inherit_interfaces defective path.
* For each of ifNum parent interface entries, scan ceNum class interfaces.
*
* @param ifNum number of entries in the implemented interface's interface list
* @param ceNum number of interfaces already on the class
* @return total pointer-comparison operations
*/
static long slow0004(int ifNum, int ceNum) {
// Class already has ceNum interfaces: IDs 0..ceNum-1
int[] ceInterfaces = new int[ceNum + ifNum];
for (int i = 0; i < ceNum; i++) {
ceInterfaces[i] = i;
}
int ceTotal = ceNum;
long ops = 0;
// iface->interfaces: IDs ceNum..ceNum+ifNum-1 (all new, no overlap)
// Worst case: none are duplicates, so every scan goes to the end
for (int k = ifNum - 1; k >= 0; k--) {
int entry = ceNum + k;
boolean found = false;
// Inner loop: O(ceNum) scan — mirrors:
// for (i = 0; i < ce_num; i++) { if (ce->interfaces[i] == entry) break; }
for (int i = 0; i < ceNum; i++) {
ops++;
if (ceInterfaces[i] == entry) {
found = true;
break;
}
}
if (!found) {
ceInterfaces[ceTotal++] = entry;
}
}
return ops;
}
/**
* Simulate zend_do_inherit_interfaces patched path.
* Pre-build HashSet of class interfaces for O(1) lookup.
*
* @param ifNum number of parent interface entries
* @param ceNum number of existing class interfaces
* @return total operations
*/
static long fast0004(int ifNum, int ceNum) {
Set<Integer> ceSet = new HashSet<>(ceNum + ifNum);
long ops = 0;
// Populate set from existing class interfaces — O(ceNum)
for (int i = 0; i < ceNum; i++) {
ceSet.add(i);
ops++;
}
for (int k = ifNum - 1; k >= 0; k--) {
int entry = ceNum + k;
ops++; // O(1) hash probe
if (!ceSet.contains(entry)) {
ceSet.add(entry);
}
}
return ops;
}
public static void main(String[] args) {
int passed = 0;
int total = 0;
// --- php-0003 tests ---
// Test 1: php-0003 N=50, ratio >= 5x
{
total++;
long sOps = slow0003(0, 50);
long fOps = fast0003(0, 50);
double ratio = (double) sOps / fOps;
boolean ok = ratio >= 5.0;
System.out.printf("Test 1 [php-0003 I=50 slow=%d fast=%d ratio=%.1fx]: %s%n",
sOps, fOps, ratio, ok ? "PASS" : "FAIL");
if (ok) passed++;
}
// Test 2: php-0003 N=200, ratio >= 30x
{
total++;
long sOps = slow0003(0, 200);
long fOps = fast0003(0, 200);
double ratio = (double) sOps / fOps;
boolean ok = ratio >= 30.0;
System.out.printf("Test 2 [php-0003 I=200 slow=%d fast=%d ratio=%.1fx]: %s%n",
sOps, fOps, ratio, ok ? "PASS" : "FAIL");
if (ok) passed++;
}
// Test 3: php-0003 N=500, ratio >= 100x
{
total++;
long sOps = slow0003(0, 500);
long fOps = fast0003(0, 500);
double ratio = (double) sOps / fOps;
boolean ok = ratio >= 100.0;
System.out.printf("Test 3 [php-0003 I=500 slow=%d fast=%d ratio=%.1fx]: %s%n",
sOps, fOps, ratio, ok ? "PASS" : "FAIL");
if (ok) passed++;
}
// Test 4: php-0003 with 20 parent + 200 new interfaces, ratio >= 10x
{
total++;
long sOps = slow0003(20, 200);
long fOps = fast0003(20, 200);
double ratio = (double) sOps / fOps;
boolean ok = ratio >= 10.0;
System.out.printf("Test 4 [php-0003 P=20+I=200 slow=%d fast=%d ratio=%.1fx]: %s%n",
sOps, fOps, ratio, ok ? "PASS" : "FAIL");
if (ok) passed++;
}
// --- php-0004 tests ---
// Test 5: php-0004 IF=50,CE=50, ratio >= 5x
{
total++;
long sOps = slow0004(50, 50);
long fOps = fast0004(50, 50);
double ratio = (double) sOps / fOps;
boolean ok = ratio >= 5.0;
System.out.printf("Test 5 [php-0004 IF=50,CE=50 slow=%d fast=%d ratio=%.1fx]: %s%n",
sOps, fOps, ratio, ok ? "PASS" : "FAIL");
if (ok) passed++;
}
// Test 6: php-0004 IF=200,CE=200, ratio >= 30x
{
total++;
long sOps = slow0004(200, 200);
long fOps = fast0004(200, 200);
double ratio = (double) sOps / fOps;
boolean ok = ratio >= 30.0;
System.out.printf("Test 6 [php-0004 IF=200,CE=200 slow=%d fast=%d ratio=%.1fx]: %s%n",
sOps, fOps, ratio, ok ? "PASS" : "FAIL");
if (ok) passed++;
}
// Test 7: php-0004 IF=500,CE=500, ratio >= 100x
{
total++;
long sOps = slow0004(500, 500);
long fOps = fast0004(500, 500);
double ratio = (double) sOps / fOps;
boolean ok = ratio >= 100.0;
System.out.printf("Test 7 [php-0004 IF=500,CE=500 slow=%d fast=%d ratio=%.1fx]: %s%n",
sOps, fOps, ratio, ok ? "PASS" : "FAIL");
if (ok) passed++;
}
// Test 8: correctness — no spurious dedup for non-overlapping sets
{
total++;
int ifNum = 50, ceNum = 50;
// Slow: count how many entries were added (should be all ifNum since no overlap)
int[] ceInterfaces = new int[ceNum + ifNum];
for (int i = 0; i < ceNum; i++) ceInterfaces[i] = i;
int ceTotal = ceNum;
for (int k = ifNum - 1; k >= 0; k--) {
int entry = ceNum + k;
boolean found = false;
for (int i = 0; i < ceNum; i++) {
if (ceInterfaces[i] == entry) { found = true; break; }
}
if (!found) ceInterfaces[ceTotal++] = entry;
}
int slowAdded = ceTotal - ceNum;
// Fast: same
Set<Integer> ceSet = new HashSet<>();
for (int i = 0; i < ceNum; i++) ceSet.add(i);
int fastAdded = 0;
for (int k = ifNum - 1; k >= 0; k--) {
int entry = ceNum + k;
if (!ceSet.contains(entry)) { ceSet.add(entry); fastAdded++; }
}
boolean ok = (slowAdded == ifNum) && (fastAdded == ifNum) && (slowAdded == fastAdded);
System.out.printf("Test 8 [php-0004 correctness added=%d expected=%d]: %s%n",
slowAdded, ifNum, ok ? "PASS" : "FAIL");
if (ok) passed++;
}
System.out.printf("%d/%d PASS%n", passed, total);
if (passed != total) System.exit(1);
}
}