| 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-2021-47335: f2fs: fix to avoid racing on fsync_entry_slab by multi filesystem instances |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| f2fs: fix to avoid racing on fsync_entry_slab by multi filesystem instances |
| |
| As syzbot reported, there is an use-after-free issue during f2fs recovery: |
| |
| Use-after-free write at 0xffff88823bc16040 (in kfence-#10): |
| kmem_cache_destroy+0x1f/0x120 mm/slab_common.c:486 |
| f2fs_recover_fsync_data+0x75b0/0x8380 fs/f2fs/recovery.c:869 |
| f2fs_fill_super+0x9393/0xa420 fs/f2fs/super.c:3945 |
| mount_bdev+0x26c/0x3a0 fs/super.c:1367 |
| legacy_get_tree+0xea/0x180 fs/fs_context.c:592 |
| vfs_get_tree+0x86/0x270 fs/super.c:1497 |
| do_new_mount fs/namespace.c:2905 [inline] |
| path_mount+0x196f/0x2be0 fs/namespace.c:3235 |
| do_mount fs/namespace.c:3248 [inline] |
| __do_sys_mount fs/namespace.c:3456 [inline] |
| __se_sys_mount+0x2f9/0x3b0 fs/namespace.c:3433 |
| do_syscall_64+0x3f/0xb0 arch/x86/entry/common.c:47 |
| entry_SYSCALL_64_after_hwframe+0x44/0xae |
| |
| The root cause is multi f2fs filesystem instances can race on accessing |
| global fsync_entry_slab pointer, result in use-after-free issue of slab |
| cache, fixes to init/destroy this slab cache only once during module |
| init/destroy procedure to avoid this issue. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47335 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.10.51 with commit 86786603014e0a22d0d6af8e80ae4b8687927048 |
| Fixed in 5.12.18 with commit 79fa5d944c875711253a23b8155b36883c696409 |
| Fixed in 5.13.3 with commit e472b276a0d2180808009be38105e12754432e2a |
| Fixed in 5.14 with commit cad83c968c2ebe97905f900326988ed37146c347 |
| |
| 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-2021-47335 |
| 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/f2fs/f2fs.h |
| fs/f2fs/recovery.c |
| fs/f2fs/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/86786603014e0a22d0d6af8e80ae4b8687927048 |
| https://git.kernel.org/stable/c/79fa5d944c875711253a23b8155b36883c696409 |
| https://git.kernel.org/stable/c/e472b276a0d2180808009be38105e12754432e2a |
| https://git.kernel.org/stable/c/cad83c968c2ebe97905f900326988ed37146c347 |
