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=-9.2 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 85BBBC43381 for ; Sat, 23 Feb 2019 21:29:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5516620665 for ; Sat, 23 Feb 2019 21:29:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550957349; bh=Z89t9QdpXqF4+TcRXl/MfORsjP6JrY8g4Bg32oSTBrs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Js8QrenUWWeqkzSYDpu2r6v1wMnYn75RjXSNAdxRdB/zxExrwGl6yNJs+SXgeGFOi zJcchP0fh3WY9QNBQG4Qg9zxpuzgdCPPsi6wjHk6Kqh+gkQHFPeQiiwe5rw/67BJS5 3WMJ+39UdfQg/mhS5YNxnoIoZzGCM8Nt0nGnn24o= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729037AbfBWV3I (ORCPT ); Sat, 23 Feb 2019 16:29:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:41756 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728753AbfBWVGi (ORCPT ); Sat, 23 Feb 2019 16:06:38 -0500 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9769D20861; Sat, 23 Feb 2019 21:06:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1550955997; bh=Z89t9QdpXqF4+TcRXl/MfORsjP6JrY8g4Bg32oSTBrs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=futBeUWqHTcPPbDv0+4syvhRCmTbwhW+PrF7Ak5td0B9hihB4vWfrV+DANJ3s+z2b wZbYQ79FPi5arBciNNUKEhSsmrfNXjDjmmqEKxUiU3pgIuiilSZbq+7wwST1AYQEcc k0PpqOjSTwXQqoh5W92VaxHn//VgkYH1HEZ+JMoA= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Pan Bian , Ian Kent , Andrew Morton , Linus Torvalds , Sasha Levin , autofs@vger.kernel.org Subject: [PATCH AUTOSEL 4.20 71/72] autofs: drop dentry reference only when it is never used Date: Sat, 23 Feb 2019 16:04:21 -0500 Message-Id: <20190223210422.199966-71-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190223210422.199966-1-sashal@kernel.org> References: <20190223210422.199966-1-sashal@kernel.org> MIME-Version: 1.0 X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pan Bian [ Upstream commit 63ce5f552beb9bdb41546b3a26c4374758b21815 ] 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. Link: http://lkml.kernel.org/r/154725122396.11260.16053424107144453867.stgit@pluto-themaw-net Signed-off-by: Pan Bian Signed-off-by: Ian Kent Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- 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 d441244b79df9..28d9c2b1b3bb3 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; } -- 2.19.1