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 X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43DC4C43441 for ; Mon, 26 Nov 2018 01:58:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B8B062084E for ; Mon, 26 Nov 2018 01:58:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="kPXTuxwz" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B8B062084E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=163.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726184AbeKZMvC (ORCPT ); Mon, 26 Nov 2018 07:51:02 -0500 Received: from m12-14.163.com ([220.181.12.14]:45641 "EHLO m12-14.163.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726079AbeKZMvC (ORCPT ); Mon, 26 Nov 2018 07:51:02 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id; bh=buvgAOLwqloDZN9VvB 9AgWN/CLf0MdCHRVAHlRRuGsI=; b=kPXTuxwzDntOWfqBCGfz3LhHGFyOauA+Av IU/iMPUHF3Pviap2/ixs9Yr/e5CgXWPWnAsSaIqkfWsHIsKf6ozQQeI0OCQNRwG9 SwievB5I+sqi//2IiALFwcADPezcfNifW4uIU2WPMZjpmGuAzZQOT2WSV1HlQbZz /xKlLWAqQ= Received: from bp.localdomain (unknown [106.120.213.96]) by smtp10 (Coremail) with SMTP id DsCowACHXNU3U_tbwMqkBw--.49337S3; Mon, 26 Nov 2018 09:58:18 +0800 (CST) From: Pan Bian To: Ian Kent Cc: autofs@vger.kernel.org, linux-kernel@vger.kernel.org, Pan Bian Subject: [PATCH] autofs: drop dentry reference only when it is never used Date: Mon, 26 Nov 2018 09:58:14 +0800 Message-Id: <1543197494-15688-1-git-send-email-bianpan2016@163.com> X-Mailer: git-send-email 2.7.4 X-CM-TRANSID: DsCowACHXNU3U_tbwMqkBw--.49337S3 X-Coremail-Antispam: 1Uf129KBjvdXoWrtr45tw4rCw43KF47WrW7urg_yoWDCrb_ua 1UurWxWrWrJr1Fya17GrWftFn3WryrJFW8Zw4Svr1agFy5KFnrW3s8Jas8urWDW347AFW5 Zr1qkr98CFy5ujkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7IU0loGPUUUUU== X-Originating-IP: [106.120.213.96] X-CM-SenderInfo: held01tdqsiiqw6rljoofrz/1tbiVBILclUMGKDOuwAAsr Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The function autofs_expire_run calls dput(dentry) to drop the reference count of dentry. However, dentry is read via autofs_dentry_ino(dentry) after that. This may result in a use-free-bug. The patch drops the reference count of dentry only when it is never used. Signed-off-by: Pan Bian --- fs/autofs/expire.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/autofs/expire.c b/fs/autofs/expire.c index d441244..28d9c2b 100644 --- a/fs/autofs/expire.c +++ b/fs/autofs/expire.c @@ -596,7 +596,6 @@ int autofs_expire_run(struct super_block *sb, pkt.len = dentry->d_name.len; memcpy(pkt.name, dentry->d_name.name, pkt.len); pkt.name[pkt.len] = '\0'; - dput(dentry); if (copy_to_user(pkt_p, &pkt, sizeof(struct autofs_packet_expire))) ret = -EFAULT; @@ -609,6 +608,8 @@ int autofs_expire_run(struct super_block *sb, complete_all(&ino->expire_complete); spin_unlock(&sbi->fs_lock); + dput(dentry); + return ret; } -- 2.7.4