linux-kernel - [PATCH v6 2/6] kernfs: Acquire kernfs_rwsem in kernfs_get_parent

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250130140207.1914339-3-bigeasy@linutronix.de>
Date: Thu, 30 Jan 2025 15:02:03 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: cgroups@...r.kernel.org,
	linux-kernel@...r.kernel.org
Cc: Michal Koutný <mkoutny@...e.com>,
	"Paul E. McKenney" <paulmck@...nel.org>,
	Boqun Feng <boqun.feng@...il.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Hillf Danton <hdanton@...a.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Marco Elver <elver@...gle.com>,
	Tejun Heo <tj@...nel.org>,
	tglx@...utronix.de,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [PATCH v6 2/6] kernfs: Acquire kernfs_rwsem in kernfs_get_parent_dentry().

kernfs_get_parent_dentry() passes kernfs_node::parent to
kernfs_get_inode().

Acquire kernfs_root::kernfs_rwsem to ensure kernfs_node::parent isn't
replaced during the operation.

Acked-by: Tejun Heo <tj@...nel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 fs/kernfs/mount.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/kernfs/mount.c b/fs/kernfs/mount.c
index 1358c21837f1a..b9b16e97bff18 100644
--- a/fs/kernfs/mount.c
+++ b/fs/kernfs/mount.c
@@ -145,7 +145,9 @@ static struct dentry *kernfs_fh_to_parent(struct super_block *sb,
 static struct dentry *kernfs_get_parent_dentry(struct dentry *child)
 {
 	struct kernfs_node *kn = kernfs_dentry_node(child);
+	struct kernfs_root *root = kernfs_root(kn);
 
+	guard(rwsem_read)(&root->kernfs_rwsem);
 	return d_obtain_alias(kernfs_get_inode(child->d_sb, kn->parent));
 }
 
-- 
2.47.2