Fix GHSA-865w-9rf3-2wh5: FPM: Logs from childrens may be altered

Author: bukka

sapi/fpm/fpm/fpm_stdio.c

@@ -229,7 +229,7 @@ static void fpm_stdio_child_said(struct fpm_event_s *ev, short which, void *arg)
 			if 	((sizeof(FPM_STDIO_CMD_FLUSH) - cmd_pos) <= in_buf &&
 					!memcmp(buf, &FPM_STDIO_CMD_FLUSH[cmd_pos], sizeof(FPM_STDIO_CMD_FLUSH) - cmd_pos)) {
 				zlog_stream_finish(log_stream);
-				start = cmd_pos;
+				start = sizeof(FPM_STDIO_CMD_FLUSH) - cmd_pos;
 			} else {
 				zlog_stream_str(log_stream, &FPM_STDIO_CMD_FLUSH[0], cmd_pos);
 			}

sapi/fpm/tests/log-bwp-msg-flush-split-sep-pos-end.phpt

@@ -0,0 +1,47 @@
+--TEST--
+FPM: Buffered worker output plain log with msg with flush split position towards separator end
+--SKIPIF--
+<?php include "skipif.inc"; ?>
+--FILE--
+<?php
+
+require_once "tester.inc";
+
+$cfg = <<<EOT
+[global]
+error_log = {{FILE:LOG}}
+[unconfined]
+listen = {{ADDR}}
+pm = dynamic
+pm.max_children = 5
+pm.start_servers = 1
+pm.min_spare_servers = 1
+pm.max_spare_servers = 3
+catch_workers_output = yes
+decorate_workers_output = no
+EOT;
+
+$code = <<<EOT
+<?php
+file_put_contents('php://stderr', str_repeat('a', 1013) . "Quarkslab\0fscf\0Quarkslab");
+EOT;
+
+$tester = new FPM\Tester($cfg, $code);
+$tester->start();
+$tester->expectLogStartNotices();
+$tester->request()->expectEmptyBody();
+$tester->expectLogLine(str_repeat('a', 1013)  . "Quarkslab", decorated: false);
+$tester->expectLogLine("Quarkslab", decorated: false);
+$tester->terminate();
+$tester->expectLogTerminatingNotices();
+$tester->close();
+
+?>
+Done
+--EXPECT--
+Done
+--CLEAN--
+<?php
+require_once "tester.inc";
+FPM\Tester::clean();
+?>

sapi/fpm/tests/log-bwp-msg-flush-split-sep-pos-start.phpt

@@ -0,0 +1,47 @@
+--TEST--
+FPM: Buffered worker output plain log with msg with flush split position towards separator start
+--SKIPIF--
+<?php include "skipif.inc"; ?>
+--FILE--
+<?php
+
+require_once "tester.inc";
+
+$cfg = <<<EOT
+[global]
+error_log = {{FILE:LOG}}
+[unconfined]
+listen = {{ADDR}}
+pm = dynamic
+pm.max_children = 5
+pm.start_servers = 1
+pm.min_spare_servers = 1
+pm.max_spare_servers = 3
+catch_workers_output = yes
+decorate_workers_output = no
+EOT;
+
+$code = <<<EOT
+<?php
+file_put_contents('php://stderr', str_repeat('a', 1009) . "Quarkslab\0fscf\0Quarkslab");
+EOT;
+
+$tester = new FPM\Tester($cfg, $code);
+$tester->start();
+$tester->expectLogStartNotices();
+$tester->request()->expectEmptyBody();
+$tester->expectLogLine(str_repeat('a', 1009)  . "Quarkslab", decorated: false);
+$tester->expectLogLine("Quarkslab", decorated: false);
+$tester->terminate();
+$tester->expectLogTerminatingNotices();
+$tester->close();
+
+?>
+Done
+--EXPECT--
+Done
+--CLEAN--
+<?php
+require_once "tester.inc";
+FPM\Tester::clean();
+?>