From patchwork Tue Jun 8 21:02:03 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Makhalov X-Patchwork-Id: 457526 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, 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 9F9A6C47082 for ; Tue, 8 Jun 2021 21:02:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 71DF661352 for ; Tue, 8 Jun 2021 21:02:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230169AbhFHVD5 (ORCPT ); Tue, 8 Jun 2021 17:03:57 -0400 Received: from ex13-edg-ou-002.vmware.com ([208.91.0.190]:42833 "EHLO EX13-EDG-OU-002.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229526AbhFHVD5 (ORCPT ); Tue, 8 Jun 2021 17:03:57 -0400 Received: from sc9-mailhost3.vmware.com (10.113.161.73) by EX13-EDG-OU-002.vmware.com (10.113.208.156) with Microsoft SMTP Server id 15.0.1156.6; Tue, 8 Jun 2021 14:02:02 -0700 Received: from amakhalov-virtual-machine.eng.vmware.com (unknown [10.118.101.187]) by sc9-mailhost3.vmware.com (Postfix) with ESMTP id 0ABCC20151; Tue, 8 Jun 2021 14:02:04 -0700 (PDT) From: Alexey Makhalov To: CC: Alexey Makhalov , Theodore Ts'o Subject: [PATCH] ext4: fix memory leak in ext4_fill_super Date: Tue, 8 Jun 2021 14:02:03 -0700 Message-ID: <20210608210203.91286-1-amakhalov@vmware.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <162315503023234@kroah.com> References: <162315503023234@kroah.com> MIME-Version: 1.0 Received-SPF: None (EX13-EDG-OU-002.vmware.com: amakhalov@vmware.com does not designate permitted sender hosts) Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org commit afd09b617db3786b6ef3dc43e28fe728cfea84df upstream. Note: this backport is only targeted for the following LTS branches: v5.4, v4.19, v4.14, v4.9 and v4.4. Buffer head references must be released before calling kill_bdev(); otherwise the buffer head (and its page referenced by b_data) will not be freed by kill_bdev, and subsequently that bh will be leaked. If blocksizes differ, sb_set_blocksize() will kill current buffers and page cache by using kill_bdev(). And then super block will be reread again but using correct blocksize this time. sb_set_blocksize() didn't fully free superblock page and buffer head, and being busy, they were not freed and instead leaked. This can easily be reproduced by calling an infinite loop of: systemctl start .mount, and systemctl stop .mount ... since systemd creates a cgroup for each slice which it mounts, and the bh leak get amplified by a dying memory cgroup that also never gets freed, and memory consumption is much more easily noticed. Fixes: ce40733ce93d ("ext4: Check for return value from sb_set_blocksize") Fixes: ac27a0ec112a ("ext4: initial copy of files from ext3") Link: https://lore.kernel.org/r/20210521075533.95732-1-amakhalov@vmware.com Signed-off-by: Alexey Makhalov Signed-off-by: Theodore Ts'o Cc: stable@vger.kernel.org # v5.4 and prior --- fs/ext4/super.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 0b364f5e6fdf..8650511ae6af 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -4066,14 +4066,20 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) } if (sb->s_blocksize != blocksize) { + /* + * bh must be released before kill_bdev(), otherwise + * it won't be freed and its page also. kill_bdev() + * is called by sb_set_blocksize(). + */ + brelse(bh); /* Validate the filesystem blocksize */ if (!sb_set_blocksize(sb, blocksize)) { ext4_msg(sb, KERN_ERR, "bad block size %d", blocksize); + bh = NULL; goto failed_mount; } - brelse(bh); logical_sb_block = sb_block * EXT4_MIN_BLOCK_SIZE; offset = do_div(logical_sb_block, blocksize); bh = sb_bread_unmovable(sb, logical_sb_block); @@ -4748,8 +4754,9 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) for (i = 0; i < EXT4_MAXQUOTAS; i++) kfree(get_qf_name(sb, sbi, i)); #endif - ext4_blkdev_remove(sbi); + /* ext4_blkdev_remove() calls kill_bdev(), release bh before it. */ brelse(bh); + ext4_blkdev_remove(sbi); out_fail: sb->s_fs_info = NULL; kfree(sbi->s_blockgroup_lock);