From ef76f1e9da864b3b39762d7f46e6d7a5cddae4c9 Mon Sep 17 00:00:00 2001 From: Tycho Andersen Date: Wed, 19 Feb 2020 12:01:29 -0700 Subject: [PATCH] cgroup1: don't call release_agent when it is "" [ Upstream commit 2e5383d7904e60529136727e49629a82058a5607 ] Older (and maybe current) versions of systemd set release_agent to "" when shutting down, but do not set notify_on_release to 0. Since 64e90a8acb85 ("Introduce STATIC_USERMODEHELPER to mediate call_usermodehelper()"), we filter out such calls when the user mode helper path is "". However, when used in conjunction with an actual (i.e. non "") STATIC_USERMODEHELPER, the path is never "", so the real usermode helper will be called with argv[0] == "". Let's avoid this by not invoking the release_agent when it is "". Signed-off-by: Tycho Andersen Signed-off-by: Tejun Heo Signed-off-by: Sasha Levin --- kernel/cgroup/cgroup-v1.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index d14896518089..545f29c5268d 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -824,7 +824,7 @@ void cgroup1_release_agent(struct work_struct *work) pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL); - if (!pathbuf || !agentbuf) + if (!pathbuf || !agentbuf || !strlen(agentbuf)) goto out; spin_lock_irq(&css_set_lock); -- 2.20.1