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Fix use of uninitialized memory in pcntl SIGCHLD handling #11536

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Fix use of uninitialized memory in pcntl SIGCHLD handling #11536

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21 changes: 9 additions & 12 deletions ext/pcntl/pcntl.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1338,15 +1338,13 @@ static void pcntl_signal_handler(int signo, siginfo_t *siginfo, void *context)
static void pcntl_signal_handler(int signo)
#endif
{
struct php_pcntl_pending_signal *psig;

psig = PCNTL_G(spares);
if (!psig) {
struct php_pcntl_pending_signal *psig_first = PCNTL_G(spares);
if (!psig_first) {
/* oops, too many signals for us to track, so we'll forget about this one */
return;
}

struct php_pcntl_pending_signal *psig_first = psig;
struct php_pcntl_pending_signal *psig = NULL;

/* Standard signals may be merged into a single one.
* POSIX specifies that SIGCHLD has the si_pid field (https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/signal.h.html),
Expand All @@ -1365,28 +1363,27 @@ static void pcntl_signal_handler(int signo)
pid = waitpid(WAIT_ANY, &status, WNOHANG | WUNTRACED);
} while (pid <= 0 && errno == EINTR);
if (pid <= 0) {
if (UNEXPECTED(psig == psig_first)) {
/* Don't handle multiple, revert back to the single signal handling. */
goto single_signal;
if (UNEXPECTED(!psig)) {
/* The child might've been consumed by another thread and will be handled there. */
return;
}
break;
}

psig = psig ? psig->next : psig_first;
psig->signo = signo;

#ifdef HAVE_STRUCT_SIGINFO_T
psig->siginfo = *siginfo;
psig->siginfo.si_pid = pid;
#endif

if (EXPECTED(psig->next)) {
psig = psig->next;
} else {
if (UNEXPECTED(!psig->next)) {
break;
}
}
} else {
single_signal:;
psig = psig_first;
psig->signo = signo;

#ifdef HAVE_STRUCT_SIGINFO_T
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9 changes: 8 additions & 1 deletion ext/pcntl/tests/gh11498.phpt
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Original file line number Diff line number Diff line change
Expand Up @@ -14,10 +14,11 @@ $processes = [];

pcntl_async_signals(true);
pcntl_signal(SIGCHLD, function($sig, $info) use (&$processes) {
echo "SIGCHLD\n";
unset($processes[$info['pid']]);
}, false);

foreach (range(0, 5) as $i) {
for ($i = 0; $i <= 5; $i++) {
$process = proc_open('echo $$ > /dev/null', [], $pipes);
$pid = proc_get_status($process)['pid'];
$processes[$pid] = $process;
Expand All @@ -32,4 +33,10 @@ while (!empty($processes) && $iters > 0) {
var_dump(empty($processes));
?>
--EXPECT--
SIGCHLD
SIGCHLD
SIGCHLD
SIGCHLD
SIGCHLD
SIGCHLD
bool(true)