linux-kernel - [PATCH] fs/namespace: fix reference leak in grab_requested_mnt

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Message-ID: <20251122071953.3053755-1-avagin@google.com>
Date: Sat, 22 Nov 2025 07:19:53 +0000
From: Andrei Vagin <avagin@...gle.com>
To: Christian Brauner <brauner@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, 
	Andrei Vagin <avagin@...gle.com>
Subject: [PATCH] fs/namespace: fix reference leak in grab_requested_mnt_ns

lookup_mnt_ns() already takes a reference on mnt_ns.
grab_requested_mnt_ns() doesn't need to take an extra reference.

Fixes: 78f0e33cd6c93 ("fs/namespace: correctly handle errors returned by grab_requested_mnt_ns")
Signed-off-by: Andrei Vagin <avagin@...gle.com>
---
 fs/namespace.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/namespace.c b/fs/namespace.c
index 2bad25709b2c..4272349650b1 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -5746,6 +5746,8 @@ static struct mnt_namespace *grab_requested_mnt_ns(const struct mnt_id_req *kreq
 
 	if (kreq->mnt_ns_id) {
 		mnt_ns = lookup_mnt_ns(kreq->mnt_ns_id);
+		if (!mnt_ns)
+			return ERR_PTR(-ENOENT);
 	} else if (kreq->mnt_ns_fd) {
 		struct ns_common *ns;
 
@@ -5761,13 +5763,12 @@ static struct mnt_namespace *grab_requested_mnt_ns(const struct mnt_id_req *kreq
 			return ERR_PTR(-EINVAL);
 
 		mnt_ns = to_mnt_ns(ns);
+		refcount_inc(&mnt_ns->passive);
 	} else {
 		mnt_ns = current->nsproxy->mnt_ns;
+		refcount_inc(&mnt_ns->passive);
 	}
-	if (!mnt_ns)
-		return ERR_PTR(-ENOENT);
 
-	refcount_inc(&mnt_ns->passive);
 	return mnt_ns;
 }
 
-- 
2.52.0.487.g5c8c507ade-goog