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Message-ID: <cbbdac31-c63c-418e-ba00-bb82b96144ee@huawei.com> Date: Mon, 30 Dec 2024 15:27:45 +0800 From: Baokun Li <libaokun1@...wei.com> To: <gregkh@...uxfoundation.org> CC: <cve@...nel.org>, <linux-cve-announce@...r.kernel.org>, <linux-kernel@...r.kernel.org>, Jan Kara <jack@...e.com>, Theodore Ts'o <tytso@....edu>, "linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>, Yang Erkun <yangerkun@...wei.com> Subject: Re: CVE-2024-50191: ext4: don't set SB_RDONLY after filesystem errors > 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
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