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,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 B145FC43441 for ; Sun, 25 Nov 2018 00:58:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F67D20874 for ; Sun, 25 Nov 2018 00:58:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="M5Rr+4os" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6F67D20874 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 S1726763AbeKYLsA (ORCPT ); Sun, 25 Nov 2018 06:48:00 -0500 Received: from m12-16.163.com ([220.181.12.16]:54106 "EHLO m12-16.163.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726323AbeKYLsA (ORCPT ); Sun, 25 Nov 2018 06:48:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:Subject:Date:Message-Id; bh=m5M4DMmmfC8+Hxib1I vpkBcysAcYi1Haj5CF53szmUY=; b=M5Rr+4osRIjWtlEQUR6z3UnVr+uw33S4oH GKRmKWFTMTeRjkYbEABpLI0EQUxfSekRGbzGT0ogLkdOjNum2wmL1TFA7fXo/Grz XTAp78fowzZiDzJX8HaZ9q0c28TahwBvn976mTKSJhQRnDbs8+QgFo9hco+wbqlX Y0mD1hHPE= Received: from bp.localdomain (unknown [106.120.213.96]) by smtp12 (Coremail) with SMTP id EMCowADHV1ef8_lbtG7IBg--.31384S3; Sun, 25 Nov 2018 08:58:10 +0800 (CST) From: Pan Bian To: Jan Kara Cc: linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Pan Bian Subject: [PATCH] ext2: fix potential use after free Date: Sun, 25 Nov 2018 08:58:02 +0800 Message-Id: <1543107482-97334-1-git-send-email-bianpan2016@163.com> X-Mailer: git-send-email 2.7.4 X-CM-TRANSID: EMCowADHV1ef8_lbtG7IBg--.31384S3 X-Coremail-Antispam: 1Uf129KBjvdXoWrtFWkZFyDtrW8Cw1UuryxuFg_yoW3Xwb_Ka 4UJw4Ikrs5GrZYq3WxAFWYy3Z5Kas5Ar1rur4rGr13ZayUtFZ7ZFyDXrWfZr15Xw47Gan8 WF4kXry3ArWIgjkaLaAFLSUrUUUUUb8apTn2vfkv8UJUUUU8Yxn0WfASr-VFAUDa7-sFnT 9fnUUvcSsGvfC2KfnxnUUI43ZEXa7IU0ubyJUUUUU== X-Originating-IP: [106.120.213.96] X-CM-SenderInfo: held01tdqsiiqw6rljoofrz/1tbiVBoKclUMGJWYxQAAs- Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The function ext2_xattr_set calls brelse(bh) to drop the reference count of bh. After that, bh may be freed. However, following brelse(bh), it reads bh->b_data via macro HDR(bh). This may result in a use-after-free bug. This patch moves brelse(bh) after reading field. Signed-off-by: Pan Bian --- fs/ext2/xattr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c index 62d9a659a..dd8f10d 100644 --- a/fs/ext2/xattr.c +++ b/fs/ext2/xattr.c @@ -612,9 +612,9 @@ bad_block: ext2_error(sb, "ext2_xattr_set", } cleanup: - brelse(bh); if (!(bh && header == HDR(bh))) kfree(header); + brelse(bh); up_write(&EXT2_I(inode)->xattr_sem); return error; -- 2.7.4