From nobody Sun Apr 19 13:43:32 2026 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 C3A1CC43334 for ; Thu, 30 Jun 2022 08:26:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233598AbiF3I0f (ORCPT ); Thu, 30 Jun 2022 04:26:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54986 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233979AbiF3I0N (ORCPT ); Thu, 30 Jun 2022 04:26:13 -0400 Received: from mail-pf1-x433.google.com (mail-pf1-x433.google.com [IPv6:2607:f8b0:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 28CC1F37 for ; Thu, 30 Jun 2022 01:26:08 -0700 (PDT) Received: by mail-pf1-x433.google.com with SMTP id k9so8234946pfg.5 for ; Thu, 30 Jun 2022 01:26:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=SypOXZhyCHcQ8uGWyAhO7T7jqGFnGubO/tkVQlNzSa4=; b=DeEze/KklMdcNbZipxXzP0SlnFO+AajUe1pUYxnUv+AWjVWwPzyohpvkUKIM4n/ryI kKqok4eZ12Vu/RmNcksSQrpSPnMPpu1xcNezPxxq6I9JPbuv3qb0Y+AaCvRwxiX/Q7HI JWc4DJw69J8+rfSzou1PE9NF5z1z/HGVXa1m6N/Q4Ck42Xjc7jOlbzS+HQoRv3qiLOpL QPekbxL+9AjUVcTADdpI6qlU706Qm1kbsDSaPdr1Lr5P/JwH4Z0CRONmPQ1PR2OiB/eo 7q/ZRWyOnANN3b/GTEKM3dFyU05OiSE5lOw6k92eR+yjqsmaGa5ZSHjEb3ZlFJp9PxGQ R+MA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=SypOXZhyCHcQ8uGWyAhO7T7jqGFnGubO/tkVQlNzSa4=; b=V9xCsU9iPpTKdTc3EdqW+4aTBhTj1opDtLHeW9FaMHVzzorkp+zAQdZhSyrbX1thM1 PV/rH2pWqLLQ0EWUG4wwMNEc2V1BM+SNLZpMSXsNZ4JmPPsoj/6AtOux3b+bNqEZKWAj 7KirICfr9SElfPpGHba5oeeB3qO/OIUAPrSXWP2CO5O9onfAtxvWuchm+e9sIa5bDltL UPW63RA4LjlQONa8fjZdz4MQXEfzNu16s4Vhbzeo7lG6X0+ySiy5HC955PhtXRWx9CbE f4p3vSquV8hQIz9pZEJdL4p3/BxeFdiLxMuiwSOF8Ykj78d8KMQLp3dgTpzjVb3qjknW QaFw== X-Gm-Message-State: AJIora85FWXKBHvA+w71C3e7pJ5qUKFaf7rwgLEkkhjzZQyYIa2vMPoh IE2Pm5mKv3KjyzQK2upnTiE= X-Google-Smtp-Source: AGRyM1uQpCyqTx3DGUB2vNh0oC2rmkVbMFyz51r1Y/mXQcmrjjX2YZ79JlIoKH3UTUsU+9gXklGZAA== X-Received: by 2002:a05:6a00:10c3:b0:525:40fe:6e8d with SMTP id d3-20020a056a0010c300b0052540fe6e8dmr14418704pfu.38.1656577567706; Thu, 30 Jun 2022 01:26:07 -0700 (PDT) Received: from localhost.localdomain ([43.132.141.3]) by smtp.gmail.com with ESMTPSA id p26-20020a056a0026da00b005251e2b53acsm12822797pfw.116.2022.06.30.01.26.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Jun 2022 01:26:07 -0700 (PDT) From: zys.zljxml@gmail.com To: tj@kernel.org, gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk Cc: linux-kernel@vger.kernel.org, Yushan Zhou Subject: [PATCH v2] kernfs: fix potential NULL dereference in __kernfs_remove Date: Thu, 30 Jun 2022 16:25:12 +0800 Message-Id: <20220630082512.3482581-1-zys.zljxml@gmail.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Yushan Zhou 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 c= heck 'kn' (see line 1346) Fixes: 393c3714081a ("kernfs: switch global kernfs_rwsem lock to per-fs loc= k") Signed-off-by: Yushan Zhou --- Change in v2: - Fix formatting issue 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; =20 + /* Short-circuit if non-root @kn has already finished removal. */ + if (!kn) + return; + lockdep_assert_held_write(&kernfs_root(kn)->kernfs_rwsem); =20 /* - * 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; =20 pr_debug("kernfs %s: removing\n", kn->name); --=20 2.27.0