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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,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 19807C3A5A9 for ; Mon, 4 May 2020 18:04:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EFF22206B8 for ; Mon, 4 May 2020 18:04:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588615480; bh=5dCP/Gb0YTMsyzKSqzDCdkXmTEkcfDYj7iiRizgRm3E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=DBmkQNtO4MdsASj1fRl8IIO57eE0+qrKOPR5gMr08VOo0YhvR2MpjFXbCSYb8F76e rG6kMCGrfXa3dLOWjFDQw6DMG3pwPj1Sp7ifDCXQxgF16ZI1rvBwN5MQE09G1nZVz9 WXVRA/drVyKrZqnc6ssbJXSct/8cQLcA9G5IxYPw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731692AbgEDSEj (ORCPT ); Mon, 4 May 2020 14:04:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:33880 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730391AbgEDSE3 (ORCPT ); Mon, 4 May 2020 14:04:29 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 99B51205ED; Mon, 4 May 2020 18:04:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588615469; bh=5dCP/Gb0YTMsyzKSqzDCdkXmTEkcfDYj7iiRizgRm3E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EYFIJ+QSrPhMzK8mzqTON0okLQr/kVzmvixeW0Fla2bDIFO6c44FG6yGulUE5CYol LUV6NT+3S0X/jC5k7/OWAaKUIfJf55lOkFcsDqTjHhAXukfJs9xkc2eN9iQ7wNdYJt fANf0gbPgHwt5I18euBE530yih5XUlHgliW3oJsw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Lukas Czerner , David Howells , Ian Kent , Al Viro , Linus Torvalds Subject: [PATCH 5.4 51/57] Fix use after free in get_tree_bdev() Date: Mon, 4 May 2020 19:57:55 +0200 Message-Id: <20200504165501.103417676@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200504165456.783676004@linuxfoundation.org> References: <20200504165456.783676004@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Howells commit dd7bc8158b413e0b580c491e8bd18cb91057c7c2 upstream. Commit 6fcf0c72e4b9, a fix to get_tree_bdev() put a missing blkdev_put() in the wrong place, before a warnf() that displays the bdev under consideration rather after it. This results in a silent lockup in printk("%pg") called via warnf() from get_tree_bdev() under some circumstances when there's a race with the blockdev being frozen. This can be caused by xfstests/tests/generic/085 in combination with Lukas Czerner's ext4 mount API conversion patchset. It looks like it ought to occur with other users of get_tree_bdev() such as XFS, but apparently doesn't. Fix this by switching the order of the lines. Fixes: 6fcf0c72e4b9 ("vfs: add missing blkdev_put() in get_tree_bdev()") Reported-by: Lukas Czerner Signed-off-by: David Howells cc: Ian Kent cc: Al Viro Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/super.c +++ b/fs/super.c @@ -1302,8 +1302,8 @@ int get_tree_bdev(struct fs_context *fc, mutex_lock(&bdev->bd_fsfreeze_mutex); if (bdev->bd_fsfreeze_count > 0) { mutex_unlock(&bdev->bd_fsfreeze_mutex); - blkdev_put(bdev, mode); warnf(fc, "%pg: Can't mount, blockdev is frozen", bdev); + blkdev_put(bdev, mode); return -EBUSY; }