| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2022-49348: ext4: filter out EXT4_FC_REPLAY from on-disk superblock field s_state |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| ext4: filter out EXT4_FC_REPLAY from on-disk superblock field s_state |
| |
| The EXT4_FC_REPLAY bit in sbi->s_mount_state is used to indicate that |
| we are in the middle of replay the fast commit journal. This was |
| actually a mistake, since the sbi->s_mount_info is initialized from |
| es->s_state. Arguably s_mount_state is misleadingly named, but the |
| name is historical --- s_mount_state and s_state dates back to ext2. |
| |
| What should have been used is the ext4_{set,clear,test}_mount_flag() |
| inline functions, which sets EXT4_MF_* bits in sbi->s_mount_flags. |
| |
| The problem with using EXT4_FC_REPLAY is that a maliciously corrupted |
| superblock could result in EXT4_FC_REPLAY getting set in |
| s_mount_state. This bypasses some sanity checks, and this can trigger |
| a BUG() in ext4_es_cache_extent(). As a easy-to-backport-fix, filter |
| out the EXT4_FC_REPLAY bit for now. We should eventually transition |
| away from EXT4_FC_REPLAY to something like EXT4_MF_REPLAY. |
| |
| The Linux kernel CVE team has assigned CVE-2022-49348 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.10.121 with commit cc5b09cb6dacd4b32640537929ab4ee8fb2b9e04 |
| Fixed in 5.15.46 with commit b99fd73418350dea360da8311e87a6a7b0e15a4c |
| Fixed in 5.17.14 with commit af2f1932743fb52ebcb008ad7ac500d9df0aa796 |
| Fixed in 5.18.3 with commit 55b4dbb29054a05d839562f6d635ce05669b016d |
| Fixed in 5.19 with commit c878bea3c9d724ddfa05a813f30de3d25a0ba83f |
| |
| 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-2022-49348 |
| 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/cc5b09cb6dacd4b32640537929ab4ee8fb2b9e04 |
| https://git.kernel.org/stable/c/b99fd73418350dea360da8311e87a6a7b0e15a4c |
| https://git.kernel.org/stable/c/af2f1932743fb52ebcb008ad7ac500d9df0aa796 |
| https://git.kernel.org/stable/c/55b4dbb29054a05d839562f6d635ce05669b016d |
| https://git.kernel.org/stable/c/c878bea3c9d724ddfa05a813f30de3d25a0ba83f |
