From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga06-in.huawei.com (szxga06-in.huawei.com [45.249.212.32]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3F6FF19F13B; Mon, 30 Dec 2024 07:27:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.32 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735543677; cv=none; b=ObkwW/c+hJ4KVHztU4gFIS5CRVebmuKenvGrKHJ20pEHzkGt5cia9gpvQkJQQSD81em1e62y8/g5D8eY6sTIz2V8TAEE9htX8z+20QAi00pgvUoJgoMnjuEOx+mYy+37AAe00JbUIN8vW6qb/fgpjHQHlqgV2kmzg06L7JodCPU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735543677; c=relaxed/simple; bh=3Qyo1LYEvOKIji4QCv9DYZM90Q/TRvs8ijEPti30AWs=; h=Message-ID:Date:MIME-Version:From:Subject:To:CC:References: In-Reply-To:Content-Type; b=e1cO+PpOISx4d3SxsklsEMyhyfY/UZo0X/AETtr/HZNvKIVDffgI7DlNaXyPed217kMI1+bd4Wd00Fc4qt31iBwu7+YyK2F+j0IlvrkDvNPmLPOqQhZs/9f+UwNGOUorXXEbH3VBSR8ClLj8kOgr9Eq3zjOL/tbuUGWvqTFpQQ4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.32 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.162.112]) by szxga06-in.huawei.com (SkyGuard) with ESMTP id 4YM7476z8hz20n5b; Mon, 30 Dec 2024 15:28:07 +0800 (CST) Received: from kwepemg500008.china.huawei.com (unknown [7.202.181.45]) by mail.maildlp.com (Postfix) with ESMTPS id 1AFF014022E; Mon, 30 Dec 2024 15:27:47 +0800 (CST) Received: from [127.0.0.1] (10.174.177.71) by kwepemg500008.china.huawei.com (7.202.181.45) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Mon, 30 Dec 2024 15:27:46 +0800 Message-ID: Date: Mon, 30 Dec 2024 15:27:45 +0800 Precedence: bulk X-Mailing-List: linux-ext4@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Baokun Li Subject: Re: CVE-2024-50191: ext4: don't set SB_RDONLY after filesystem errors To: CC: , , , Jan Kara , Theodore Ts'o , "linux-ext4@vger.kernel.org" , Yang Erkun References: <2024110851-CVE-2024-50191-f31c@gregkh> Content-Language: en-US In-Reply-To: <2024110851-CVE-2024-50191-f31c@gregkh> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: dggems704-chm.china.huawei.com (10.3.19.181) To kwepemg500008.china.huawei.com (7.202.181.45) > Description > =========== > > In the Linux kernel, the following vulnerability has been resolved: > > ext4: don't set SB_RDONLY after filesystem errors > > When the filesystem is mounted with errors=remount-ro, we were setting > SB_RDONLY flag to stop all filesystem modifications. We knew this misses > proper locking (sb->s_umount) and does not go through proper filesystem > remount procedure but it has been the way this worked since early ext2 > days and it was good enough for catastrophic situation damage > mitigation. Recently, syzbot has found a way (see link) to trigger > warnings in filesystem freezing because the code got confused by > SB_RDONLY changing under its hands. Since these days we set > EXT4_FLAGS_SHUTDOWN on the superblock which is enough to stop all > filesystem modifications, modifying SB_RDONLY shouldn't be needed. So > stop doing that. > > The Linux kernel CVE team has assigned CVE-2024-50191 to this issue. > > > Affected and fixed versions > =========================== > >     Fixed in 5.15.168 with commit fbb177bc1d64 >     Fixed in 6.1.113 with commit 4061e07f040a Since 6.1 and 5.15 don't have backport     commit 95257987a638 ("ext4: drop EXT4_MF_FS_ABORTED flag"), we won't set the EXT4_FLAGS_SHUTDOWN bit in ext4_handle_error() yet. So here these two commits cause us to repeatedly get the following printout: [   42.993195] EXT4-fs error (device sda): ext4_journal_check_start:83: comm fsstress: Detected aborted journal [   42.993351] EXT4-fs error (device sda): ext4_journal_check_start:83: comm fsstress: Detected aborted journal [   42.993483] EXT4-fs error (device sda): ext4_journal_check_start:83: comm fsstress: Detected aborted journal [   42.993597] EXT4-fs error (device sda): ext4_journal_check_start:83: comm fsstress: Detected aborted journal [   42.993638] EXT4-fs error (device sda): ext4_journal_check_start:83: comm fsstress: Detected aborted journal [   42.993718] EXT4-fs error (device sda): ext4_journal_check_start:83: comm fsstress: Detected aborted journal [   42.993866] EXT4-fs error (device sda): ext4_journal_check_start:83: comm fsstress: Detected aborted journal [   42.993874] EXT4-fs error (device sda): ext4_journal_check_start:83: comm fsstress: Detected aborted journal [   42.993874] EXT4-fs error (device sda) in __ext4_new_inode:1089: Journal has aborted [   42.994059] EXT4-fs error (device sda): ext4_journal_check_start:83: comm fsstress: Detected aborted journal [   42.999893] EXT4-fs: 58002 callbacks suppressed [   42.999895] EXT4-fs (sda): Remounting filesystem read-only [   43.000110] EXT4-fs (sda): Remounting filesystem read-only [   43.000274] EXT4-fs (sda): Remounting filesystem read-only [   43.000421] EXT4-fs (sda): Remounting filesystem read-only [   43.000569] EXT4-fs (sda): Remounting filesystem read-only [   43.000701] EXT4-fs (sda): Remounting filesystem read-only [   43.000869] EXT4-fs (sda): Remounting filesystem read-only [   43.001094] EXT4-fs (sda): Remounting filesystem read-only [   43.001229] EXT4-fs (sda): Remounting filesystem read-only [   43.001365] EXT4-fs (sda): Remounting filesystem read-only Perhaps we should revert both commits. Thanks, Baokun >     Fixed in 6.6.57 with commit 58c0648e4c77 >     Fixed in 6.11.4 with commit ee77c3884691 >     Fixed in 6.12-rc1 with commit d3476f3dad4a > > Please see https://www.kernel.org for a full list of currently supported > kernel versions by the kernel community. > > Unaffected versions might change over time as fixes are backported to > older supported kernel versions.  The official CVE entry at > https://cve.org/CVERecord/?id=CVE-2024-50191 > will be updated if fixes are backported, please check that for the most > up to date information about this issue. > > > Affected files > ============== > > The file(s) affected by this issue are: >     fs/ext4/super.c > > > Mitigation > ========== > > The Linux kernel CVE team recommends that you update to the latest > stable kernel version for this, and many other bugfixes. Individual > changes are never tested alone, but rather are part of a larger kernel > release.  Cherry-picking individual commits is not recommended or > supported by the Linux kernel community at all.  If however, updating to > the latest release is impossible, the individual changes to resolve this > issue can be found at these commits: > https://git.kernel.org/stable/c/fbb177bc1d6487cd3e9b50ae0be2781b7297980d > https://git.kernel.org/stable/c/4061e07f040a091f694f461b86a26cf95ae66439 > https://git.kernel.org/stable/c/58c0648e4c773f5b54f0cb63bc8c7c6bf52719a9 > https://git.kernel.org/stable/c/ee77c388469116565e009eaa704a60bc78489e09 > https://git.kernel.org/stable/c/d3476f3dad4ad68ae5f6b008ea6591d1520da5d8