From nobody Mon Feb 9 16:16:45 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 64DFD18B476; Tue, 28 Jan 2025 08:42:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738053758; cv=none; b=M2ZOem6p6CSNAjMBmPAPI5KGGg4mK7U3ulywUsaiKCzkNV273qXYItUBNvRDlIhHPeG39Y4zQxAsqIabFejf/f6J04eTjI2FeW7iBUjnEsDHFtg8XRCnmDhxJmpZtitjgBZPedStYvYEgNVgvxMiFfHXvOIJvYwkF8V9yw+HB6Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738053758; c=relaxed/simple; bh=O7QYnNqtfos+KX02uWpBSuTC6KY2eysR/3Ql446iBi8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=HTJjppFsi+1hWjpKoHg4cufwSWwXjVQhGGF6c5Kjn9KJC1Jv/UEhycuNaAvW53ThglYJuugl70v3qbp07r08EToHtjyCQWIKftgIqCQcDt74xbs26ORZCKh1pCaI5XA08fIR8NN0P8czYd/JtGZ9iRIxMcUU6i3SZcVvgNgZ9Us= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=mk9aIm8p; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=V/1FyF1E; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="mk9aIm8p"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="V/1FyF1E" From: Sebastian Andrzej Siewior DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1738053755; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=70ZpbL95PFOkiQLvqaDhiqcr9y/+An7eazJ7AAHJWk4=; b=mk9aIm8pvzmp8LFMYBvY2ouAaIONV2R98V5ypGvjssokmV4CmSViqD1uX6TsYt/AH87CA/ HlhIwAbcH+j08SYW7gZR7cxvchH3k2toeyQBGV294S6hj+qo5TJoyPv3oFtPqXguROPu+f jWIr+lLLflfSiylQd9FJ8fxURAGexcbAHB6WnSadQFEIGP26GymDSu+GfYcv3P3tUGheDb EJrmF8OMBCN4C/JYDQgbnaXCBrSfdtbD+LM/ALtWm1GhRYfKURrVSgQWbby5Xbc9PlTyL9 kdckCITEM5Q45U6hHHD3uN5pn400bSFh+cbu+nMlr4rQ5169UEh7B/hPgqQPTw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1738053755; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=70ZpbL95PFOkiQLvqaDhiqcr9y/+An7eazJ7AAHJWk4=; b=V/1FyF1E4oiv459EHmFtXZtVoOfZGCQiVU13YduLGk8YeH70i5yFkNHBKxOgOrNIsL3r5x N7bnVcJa4qM+ykBQ== To: cgroups@vger.kernel.org, linux-kernel@vger.kernel.org Cc: =?UTF-8?q?Michal=20Koutn=C3=BD?= , "Paul E. McKenney" , Boqun Feng , Greg Kroah-Hartman , Hillf Danton , Johannes Weiner , Marco Elver , Tejun Heo , tglx@linutronix.de, Sebastian Andrzej Siewior Subject: [PATCH v5 1/6] kernfs: Acquire kernfs_rwsem in kernfs_notify_workfn(). Date: Tue, 28 Jan 2025 09:42:21 +0100 Message-ID: <20250128084226.1499291-2-bigeasy@linutronix.de> In-Reply-To: <20250128084226.1499291-1-bigeasy@linutronix.de> References: <20250128084226.1499291-1-bigeasy@linutronix.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" kernfs_notify_workfn() dereferences kernfs_node::name and passes it later to fsnotify(). If the node is renamed then the previously observed name pointer becomes invalid. Acquire kernfs_root::kernfs_rwsem to block renames of the node. Acked-by: Tejun Heo Signed-off-by: Sebastian Andrzej Siewior --- fs/kernfs/file.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c index 8502ef68459b9..165d8e37976ba 100644 --- a/fs/kernfs/file.c +++ b/fs/kernfs/file.c @@ -911,6 +911,7 @@ static void kernfs_notify_workfn(struct work_struct *wo= rk) /* kick fsnotify */ =20 down_read(&root->kernfs_supers_rwsem); + down_read(&root->kernfs_rwsem); list_for_each_entry(info, &kernfs_root(kn)->supers, node) { struct kernfs_node *parent; struct inode *p_inode =3D NULL; @@ -947,6 +948,7 @@ static void kernfs_notify_workfn(struct work_struct *wo= rk) iput(inode); } =20 + up_read(&root->kernfs_rwsem); up_read(&root->kernfs_supers_rwsem); kernfs_put(kn); goto repeat; --=20 2.47.2