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Fix GH-16811: Crash in zend_test observer on runtime observe_function_names change #21635

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Fix GH-16811: Crash in zend_test observer on runtime observe_function_names change #21635

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e637891
Fix GH-16811: Crash in zend_test observer on runtime observe_function…
iliaal Apr 4, 2026
cdf733a
Fix gh16811.phpt on CircleCI ARM
iliaal Apr 4, 2026
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9 changes: 7 additions & 2 deletions ext/zend_test/observer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -334,7 +334,8 @@ static ZEND_INI_MH(zend_test_observer_OnUpdateCommaList)
}
if (stage != PHP_INI_STAGE_STARTUP && stage != PHP_INI_STAGE_ACTIVATE && stage != PHP_INI_STAGE_DEACTIVATE && stage != PHP_INI_STAGE_SHUTDOWN) {
ZEND_HASH_FOREACH_STR_KEY(*p, funcname) {
if ((func = zend_hash_find_ptr(EG(function_table), funcname))) {
if ((func = zend_hash_find_ptr(EG(function_table), funcname))
&& RUN_TIME_CACHE(&func->common)) {
void *old_handler;
zend_observer_remove_begin_handler(func, observer_begin, (zend_observer_fcall_begin_handler *)&old_handler);
zend_observer_remove_end_handler(func, observer_end, (zend_observer_fcall_end_handler *)&old_handler);
Expand All @@ -357,7 +358,11 @@ static ZEND_INI_MH(zend_test_observer_OnUpdateCommaList)
zend_string_release(str);
if (stage != PHP_INI_STAGE_STARTUP && stage != PHP_INI_STAGE_ACTIVATE && stage != PHP_INI_STAGE_DEACTIVATE && stage != PHP_INI_STAGE_SHUTDOWN) {
ZEND_HASH_FOREACH_STR_KEY(*p, funcname) {
if ((func = zend_hash_find_ptr(EG(function_table), funcname))) {
if ((func = zend_hash_find_ptr(EG(function_table), funcname))
&& RUN_TIME_CACHE(&func->common) && *ZEND_OBSERVER_DATA(func)) {
void *old_handler;
zend_observer_remove_begin_handler(func, observer_begin, (zend_observer_fcall_begin_handler *)&old_handler);
zend_observer_remove_end_handler(func, observer_end, (zend_observer_fcall_end_handler *)&old_handler);
Comment on lines +363 to +365
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@iluuu1994 iluuu1994 Apr 4, 2026

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I don't understand why this is needed. Any previous handlers should have been removed above, no?

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@iliaal iliaal Apr 4, 2026

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The first loop only removes handlers for functions in the previous comma list. If observe_all=1 installed the handler at first-call time (via observer_fcall_init), that function was never in the old comma list, so the first loop won't touch it. Without the remove here, add_begin_handler installs a duplicate and hits ZEND_UNREACHABLE().

The *ZEND_OBSERVER_DATA(func) check gates this: we only attempt removal when observer data already exists.

zend_observer_add_begin_handler(func, observer_begin);
zend_observer_add_end_handler(func, observer_end);
}
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18 changes: 18 additions & 0 deletions ext/zend_test/tests/gh16811.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
--TEST--
GH-16811 (Segmentation fault in zend observer)
--EXTENSIONS--
zend_test
--INI--
zend_test.observer.enabled=1
zend_test.observer.show_output=1
zend_test.observer.observe_function_names=a,d
--FILE--
<?php
var_dump(ini_set("zend_test.observer.observe_function_names", "bar"));
function d() {}
?>
--EXPECTF--
<!-- init '%s' -->
<!-- init ini_set() -->
<!-- init var_dump() -->
string(3) "a,d"
17 changes: 17 additions & 0 deletions ext/zend_test/tests/gh16811_observe_all.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,17 @@
--TEST--
GH-16811 (Assertion failure adding duplicate observer handler)
--EXTENSIONS--
zend_test
--INI--
zend_test.observer.enabled=1
zend_test.observer.observe_all=1
zend_test.observer.show_output=0
--FILE--
<?php
function foo() {}
foo();
ini_set("zend_test.observer.observe_function_names", "foo");
echo "Done\n";
?>
--EXPECT--
Done
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