linux-kernel - [PATCH 2/2] cgroup: Fix reference count leak when cft->open is NULL

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Message-ID: <20250718115409.878122-2-kerayhuang@tencent.com>
Date: Fri, 18 Jul 2025 19:54:09 +0800
From: Zijiang Huang <huangzjsmile@...il.com>
To: tj@...nel.org,
	hannes@...xchg.org,
	mkoutny@...e.com
Cc: cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Zijiang Huang <kerayhuang@...cent.com>,
	Hao Peng <flyingpeng@...cent.com>
Subject: [PATCH 2/2] cgroup: Fix reference count leak when cft->open is NULL

When cft->open is NULL, it will cause ctx namespace reference count leak.

Signed-off-by: Zijiang Huang <kerayhuang@...cent.com>
Reviewed-by: Hao Peng <flyingpeng@...cent.com>
---
 kernel/cgroup/cgroup.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index a723b7dc6e4e..9bde0f4be687 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -4134,8 +4134,10 @@ static int cgroup_file_open(struct kernfs_open_file *of)
 	get_cgroup_ns(ctx->ns);
 	of->priv = ctx;
 
-	if (!cft->open)
+	if (!cft->open) {
+		get_cgroup_ns(ctx->ns);
 		return 0;
+	}
 
 	ret = cft->open(of);
 	if (ret) {
-- 
2.43.5