# CVE-2021-47335: linux: In the Linux kernel, the following vulnerability has been resolved:  f2fs: fix to avoid racing on fsync_entry_slab by...

CVE-2021-47335 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47335, released May 21, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-47335
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0023
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 21, 2024

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.14.6-1 | [DEBIAN-CVE-2021-47335](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47335.md) | May 21, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.14.6-1 | [DEBIAN-CVE-2021-47335](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47335.md) | May 21, 2024 |
| Linux | linux Debian 14 | 5.14.6-1 | [DEBIAN-CVE-2021-47335](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47335.md) | May 21, 2024 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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