linux-kernel - [PATCH 2/2] debugfs: do not attempt to create a new file before the filesystem is initalized

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Date:   Thu, 18 Feb 2021 11:08:18 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Michael Walle <michael@...le.cc>,
        Marc Zyngier <maz@...nel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        stable <stable@...r.kernel.org>
Subject: [PATCH 2/2] debugfs: do not attempt to create a new file before the filesystem is initalized

Some subsystems want to add debugfs files at early boot, way before
debugfs is initialized.  This seems to work somehow as the vfs layer
will not allow it to happen, but let's be explicit and test to ensure we
are properly up and running before allowing files to be created.

Reported-by: Michael Walle <michael@...le.cc>
Reported-by: Marc Zyngier <maz@...nel.org>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>
Cc: stable <stable@...r.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/debugfs/inode.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index bbeb563cbe78..86c7f0489620 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -318,6 +318,9 @@ static struct dentry *start_creating(const char *name, struct dentry *parent)
 	if (!(debugfs_allow & DEBUGFS_ALLOW_API))
 		return ERR_PTR(-EPERM);
 
+	if (!debugfs_initialized())
+		return ERR_PTR(-ENOENT);
+
 	pr_debug("creating file '%s'\n", name);
 
 	if (IS_ERR(parent))
-- 
2.30.1