From nobody Sun Apr 19 13:43:30 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 B1A76C433EF for ; Thu, 30 Jun 2022 04:01:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232080AbiF3EBf (ORCPT ); Thu, 30 Jun 2022 00:01:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52172 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232194AbiF3EBM (ORCPT ); Thu, 30 Jun 2022 00:01:12 -0400 Received: from mail-pl1-x62c.google.com (mail-pl1-x62c.google.com [IPv6:2607:f8b0:4864:20::62c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 862E23916C for ; Wed, 29 Jun 2022 21:00:55 -0700 (PDT) Received: by mail-pl1-x62c.google.com with SMTP id o18so15924192plg.2 for ; Wed, 29 Jun 2022 21:00:55 -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=ggFb66b2FdfhJM6RYYDPcnqe4LFasg+9yoyX1GLgz8Y=; b=CavkeJHNbx4rkrcSihwEKVaSnfnToWrzXmPPuZwWD2q9V+Elv2sx4sI+VUX/PRDEt9 Uuef9hwROdzCDzEQ2nZCVjNrHGYKtRjbXK5SD4FC1BJlVhNEz4mG/irTrl7ILMM8ZuqU SI5Qf/Ho7NrZjIKipFa+dgpfp7HPDmEOpRifYfgEmUBhXlrjDmD8ulMgRL4Lq8wFfI3m fq1A938sdkXA1Z/jIDtBdt0BidtmURD3HYrMatm6VOswiyTuDnH/r+U3OoUzbt9e1WOg pQRrZBH0Qqbm0TEGFf2kUUKpLD/kLgiC4zXzXZ2KAkSvXbsuS3sVr+udshl/UgCKcAUm l+Og== 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=ggFb66b2FdfhJM6RYYDPcnqe4LFasg+9yoyX1GLgz8Y=; b=oyDaqDsrOQGfilg8Y1LfjZmPDcmm+g4IJjxaa5q9MZQk8Z6Ui98vbuzslNoDZd7NYO RANNJ7NJzW6DqJfb7qU20IEH9aiSWrlzrSmUZ7JtVuLz0Y8UAI4AHC+fMvODvQE47peM 6W2Nd8x7T+3+lI0eBSg8gGg70hCSeS8AEQvr+vY8qLv2vwOHlNFe6GwyzvtXXslXeNLt Tm+8oa46/mA/4PX1mvgd/8mEQnnqPs6ox84elptbDmcYlEWFoxGx8jLPKuxWFKyb2C9v z4k0Txn3dQVIXWoAZPuNu5B5xdn5CYYO6jXg+0eY6Uw4N43CJrTj5cBdfpQ3psUZJ4vd mKyQ== X-Gm-Message-State: AJIora88sCuRH0AEDxwBPa1TtoXnGSrf3RqAFAQOMP91A9Fby6DQoF1A tpL9beATdvGFkOZeyOckWGsUMoyG198YWg== X-Google-Smtp-Source: AGRyM1tf8y61iQUgmX0fbGLuWJi8dr4R2Tf9rJwcHZU796RX76U7NBtf053AViT9J+jWOfyNh2LgVQ== X-Received: by 2002:a17:90b:390c:b0:1ec:ae13:c5aa with SMTP id ob12-20020a17090b390c00b001ecae13c5aamr9553485pjb.64.1656561655015; Wed, 29 Jun 2022 21:00:55 -0700 (PDT) Received: from localhost.localdomain ([43.132.141.3]) by smtp.gmail.com with ESMTPSA id h13-20020a170902f7cd00b001651562eb16sm12203020plw.124.2022.06.29.21.00.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 29 Jun 2022 21:00:54 -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, katrinzhou Subject: [PATCH] kernfs: fix potential NULL dereference in __kernfs_remove Date: Thu, 30 Jun 2022 12:00:47 +0800 Message-Id: <20220630040047.3241781-1-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: katrinzhou When lockdep is enabled, lockdep_assert_held_write would cause potential NULL pointer dereference. Fix the folloeing smatch warnings: fs/kernfs/dir.c:1353 __kernfs_remove() warn: variable dereferenced before c= heck 'kn' (see line 1346) Signed-off-by: katrinzhou --- 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