From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 841F3C00140 for ; Mon, 15 Aug 2022 21:54:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349678AbiHOVy4 (ORCPT ); Mon, 15 Aug 2022 17:54:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43770 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350586AbiHOVvm (ORCPT ); Mon, 15 Aug 2022 17:51:42 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C53FD106FB3; Mon, 15 Aug 2022 12:33:10 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E14C960FB9; Mon, 15 Aug 2022 19:33:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9B440C433D6; Mon, 15 Aug 2022 19:33:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1660591989; bh=8O+aw44hiz3gQ+R3zmwagrKbzLPzdYibj+A58m4ChMI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Qupxr4FQ59hXqUMVt4lNhtKeBGAVS8TtDm3MFPKVeNOrD7muqwhvjGVXe+how6/vT EPYf1N2mvc+d2bw/xCzVX16mpFZNFIuZ2Nl0mXLE4wOszALX7BnuCjl99NCSOWzu16 lNVAy3pbfw7uioespEoAaY5z1hKaZC6Y/XTaLkmA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Yushan Zhou , Sasha Levin Subject: [PATCH 5.18 0714/1095] kernfs: fix potential NULL dereference in __kernfs_remove Date: Mon, 15 Aug 2022 20:01:53 +0200 Message-Id: <20220815180458.935428494@linuxfoundation.org> X-Mailer: git-send-email 2.37.2 In-Reply-To: <20220815180429.240518113@linuxfoundation.org> References: <20220815180429.240518113@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yushan Zhou [ Upstream commit 72b5d5aef246a0387cefa23121dd90901c7a691a ] When lockdep is enabled, lockdep_assert_held_write would cause potential NULL pointer dereference. Fix the following smatch warnings: fs/kernfs/dir.c:1353 __kernfs_remove() warn: variable dereferenced before check 'kn' (see line 1346) Fixes: 393c3714081a ("kernfs: switch global kernfs_rwsem lock to per-fs lock") Signed-off-by: Yushan Zhou Link: https://lore.kernel.org/r/20220630082512.3482581-1-zys.zljxml@gmail.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- fs/kernfs/dir.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c index 6eca72cfa1f2..1cc88ba6de90 100644 --- a/fs/kernfs/dir.c +++ b/fs/kernfs/dir.c @@ -1343,14 +1343,17 @@ static void __kernfs_remove(struct kernfs_node *kn) { struct kernfs_node *pos; + /* Short-circuit if non-root @kn has already finished removal. */ + if (!kn) + return; + lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem); /* - * Short-circuit if non-root @kn has already finished removal. * This is for kernfs_remove_self() which plays with active ref * after removal. */ - if (!kn || (kn->parent && RB_EMPTY_NODE(&kn->rb))) + if (kn->parent && RB_EMPTY_NODE(&kn->rb)) return; pr_debug("kernfs %s: removing\n", kn->name); -- 2.35.1