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fix: add guards to oapi cufa opcode check #708

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merged 3 commits into from
Aug 9, 2023
Merged

fix: add guards to oapi cufa opcode check #708

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94c04a3
fix: add guards to oapi cufa opcode check
ZNeumann Jul 28, 2023
f56cbb0
docs: comment clarity
ZNeumann Aug 3, 2023
0b4d8db
Update agent/php_execute.c
ZNeumann Aug 8, 2023
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35 changes: 28 additions & 7 deletions agent/php_execute.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1934,6 +1934,7 @@ static void nr_php_observer_attempt_call_cufa_handler(NR_EXECUTE_PROTO) {
nrl_verbosedebug(NRL_AGENT, "%s: cannot get previous execute data", __func__);
return;
}

if (NULL == execute_data->prev_execute_data->opline) {
nrl_verbosedebug(NRL_AGENT, "%s: cannot get previous opline", __func__);
return;
Expand Down Expand Up @@ -1966,20 +1967,40 @@ static void nr_php_observer_attempt_call_cufa_handler(NR_EXECUTE_PROTO) {
* cause additional performance overhead, this should be considered a last
* resort.
*/
const zend_op* prev_opline = execute_data->prev_execute_data->opline - 1;

/*
* We cannot safely access the opline of internal functions, and we only
* want to instrument cufa calls from user functions anyway
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*/
if (UNEXPECTED(NULL == execute_data->prev_execute_data->func)) {
nrl_verbosedebug(NRL_AGENT, "%s: cannot get previous function", __func__);
return;
}
if (!ZEND_USER_CODE(execute_data->prev_execute_data->func->type)) {
nrl_verbosedebug(NRL_AGENT, "%s: caller is php internal function", __func__);
return;
}

const zend_op* prev_opline = execute_data->prev_execute_data->opline;

/*
* Extra safety check. Previously, we instrumented by overwritting ZEND_DO_FCALL.
* Within OAPI, for consistency's sake, we will ensure the same
*/
if (ZEND_DO_FCALL != prev_opline->opcode) {
nrl_verbosedebug(NRL_AGENT, "%s: cannot get previous function name", __func__);
return;
}
prev_opline -= 1; // Checks previous opcode
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if (ZEND_CHECK_UNDEF_ARGS == prev_opline->opcode) {
prev_opline = execute_data->prev_execute_data->opline - 2;
prev_opline -= 1; // Checks previous opcode
}
if (ZEND_SEND_ARRAY == prev_opline->opcode) {

if (UNEXPECTED((NULL == execute_data->func))) {
nrl_verbosedebug(NRL_AGENT, "%s: cannot get current function", __func__);
return;
}
if (UNEXPECTED(NULL == execute_data->prev_execute_data->func)) {
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nrl_verbosedebug(NRL_AGENT, "%s: cannot get previous function", __func__);
return;
}

if (UNEXPECTED(NULL == execute_data->prev_execute_data->func->common.function_name)) {
nrl_verbosedebug(NRL_AGENT, "%s: cannot get previous function name", __func__);
return;
Expand Down
10 changes: 10 additions & 0 deletions tests/integration/frameworks/wordpress/test_wordpress_do_action.php8.php
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@
*/

/*EXPECT
g
f
h
g
Expand Down Expand Up @@ -70,4 +71,13 @@ function f() {
}
}

/*
* Initiates a non-flattened call stack of internal->user_code
* to ensure that cufa instrumentation properly handles skipping
* opline lookups of internal functions
*/
$function = new ReflectionFunction('g');
$function->invoke();


do_action("f");
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