From: Willy Tarreau <w@1wt.eu>
Date: Fri, 15 Jul 2022 10:08:40 +0000 (+0200)
Subject: BUG/MEDIUM: cli/threads: make "show threads" more robust on applets
X-Git-Tag: v2.7-dev2~52
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=52f238d32601b513ef4716c55c01b5dd0afc548a;p=thirdparty%2Fhaproxy.git

BUG/MEDIUM: cli/threads: make "show threads" more robust on applets

Running several concurrent "show threads" in loops might occasionally
cause a segfault when trying to retrieve the stream from appctx_sc()
which may be null while the applet is finishing. It's not easy to
reproduce, it requires 3-5 sessions in parallel for about a minute
or so. The appctx_sc must be checked before passing it to sc_strm().

This must be backported to 2.6 which also has the bug.
---

diff --git a/src/debug.c b/src/debug.c
index b793e3ec03..74249ff513 100644
--- a/src/debug.c
+++ b/src/debug.c
@@ -226,6 +226,7 @@ void ha_task_dump(struct buffer *buf, const struct task *task, const char *pfx)
 	const struct stream *s = NULL;
 	const struct appctx __maybe_unused *appctx = NULL;
 	struct hlua __maybe_unused *hlua = NULL;
+	const struct stconn *sc;
 
 	if (!task) {
 		chunk_appendf(buf, "0\n");
@@ -256,8 +257,8 @@ void ha_task_dump(struct buffer *buf, const struct task *task, const char *pfx)
 
 	if (task->process == process_stream && task->context)
 		s = (struct stream *)task->context;
-	else if (task->process == task_run_applet && task->context)
-		s = sc_strm(appctx_sc((struct appctx *)task->context));
+	else if (task->process == task_run_applet && task->context && (sc = appctx_sc((struct appctx *)task->context)))
+		s = sc_strm(sc);
 	else if (task->process == sc_conn_io_cb && task->context)
 		s = sc_strm(((struct stconn *)task->context));