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 <[email protected]>
---
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 be1a1c83cdd1..b3626c3c6f92 100644
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -782,7 +782,7 @@ 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
On Wed, Feb 19, 2020 at 12:01:29PM -0700, Tycho Andersen wrote:
> 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 <[email protected]>
Applied to cgroup/for-5.6-fixes.
Thanks.
--
tejun