# CVE-2023-54165: zsmalloc: move LRU update from zs_map_object() to zs_malloc()

> A race condition in the Linux kernel zsmalloc subsystem can cause a list corruption crash under memory pressure, leading to denial of service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 30 Dec 2025
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2023-54165, GHSA-wjwc-m4x2-6jp9, UBUNTU-CVE-2023-54165

## What is CVE-2023-54165?

CVE-2023-54165 is a high-severity vulnerability in Linux, published on 30 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

zsmalloc: move LRU update from zs_map_object() to zs_malloc()

Under memory pressure, we sometimes observe the following crash:

[ 5694.832838] ------------[ cut here ]------------
[ 5694.842093] list_del corruption, ffff888014b6a448->next is LIST_POISON1 (dead000000000100)
[ 5694.858677] WARNING: CPU: 33 PID: 418824 at lib/list_debug.c:47 __list_del_entry_valid+0x42/0x80
[ 5694.961820] CPU: 33 PID: 418824 Comm: fuse_counters.s Kdump: loaded Tainted: G S                5.19.0-0_fbk3_rc3_hoangnhatpzsdynshrv41_10870_g85a9558a25de #1
[ 5694.990194] Hardware name: Wiwynn Twin Lakes MP/Twin Lakes Passive MP, BIOS YMM16 05/24/2021
[ 5695.007072] RIP: 0010:__list_del_entry_valid+0x42/0x80
[ 5695.017351] Code: 08 48 83 c2 22 48 39 d0 74 24 48 8b 10 48 39 f2 75 2c 48 8b 51 08 b0 01 48 39 f2 75 34 c3 48 c7 c7 55 d7 78 82 e8 4e 45 3b 00 <0f> 0b eb 31 48 c7 c7 27 a8 70 82 e8 3e 45 3b 00 0f 0b eb 21 48 c7
[ 5695.054919] RSP: 0018:ffffc90027aef4f0 EFLAGS: 00010246
[ 5695.065366] RAX: 41fe484987275300 RBX: ffff888008988180 RCX: 0000000000000000
[ 5695.079636] RDX: ffff88886006c280 RSI: ffff888860060480 RDI: ffff888860060480
[ 5695.093904] RBP: 0000000000000002 R08: 0000000000000000 R09: ffffc90027aef370
[ 5695.108175] R10: 0000000000000000 R11: ffffffff82fdf1c0 R12: 0000000010000002
[ 5695.122447] R13: ffff888014b6a448 R14: ffff888014b6a420 R15: 00000000138dc240
[ 5695.136717] FS:  00007f23a7d3f740(0000) GS:ffff888860040000(0000) knlGS:0000000000000000
[ 5695.152899] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 5695.164388] CR2: 0000560ceaab6ac0 CR3: 000000001c06c001 CR4: 00000000007706e0
[ 5695.178659] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 5695.192927] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 5695.207197] PKRU: 55555554
[ 5695.212602] Call Trace:
[ 5695.217486]  <TASK>
[ 5695.221674]  zs_map_object+0x91/0x270
[ 5695.229000]  zswap_frontswap_store+0x33d/0x870
[ 5695.237885]  ? do_raw_spin_lock+0x5d/0xa0
[ 5695.245899]  __frontswap_store+0x51/0xb0
[ 5695.253742]  swap_writepage+0x3c/0x60
[ 5695.261063]  shrink_page_list+0x738/0x1230
[ 5695.269255]  shrink_lruvec+0x5ec/0xcd0
[ 5695.276749]  ? shrink_slab+0x187/0x5f0
[ 5695.284240]  ? mem_cgroup_iter+0x6e/0x120
[ 5695.292255]  shrink_node+0x293/0x7b0
[ 5695.299402]  do_try_to_free_pages+0xea/0x550
[ 5695.307940]  try_to_free_pages+0x19a/0x490
[ 5695.316126]  __folio_alloc+0x19ff/0x3e40
[ 5695.323971]  ? __filemap_get_folio+0x8a/0x4e0
[ 5695.332681]  ? walk_component+0x2a8/0xb50
[ 5695.340697]  ? generic_permission+0xda/0x2a0
[ 5695.349231]  ? __filemap_get_folio+0x8a/0x4e0
[ 5695.357940]  ? walk_component+0x2a8/0xb50
[ 5695.365955]  vma_alloc_folio+0x10e/0x570
[ 5695.373796]  ? walk_component+0x52/0xb50
[ 5695.381634]  wp_page_copy+0x38c/0xc10
[ 5695.388953]  ? filename_lookup+0x378/0xbc0
[ 5695.397140]  handle_mm_fault+0x87f/0x1800
[ 5695.405157]  do_user_addr_fault+0x1bd/0x570
[ 5695.413520]  exc_page_fault+0x5d/0x110
[ 5695.421017]  asm_exc_page_fault+0x22/0x30

After some investigation, I have found the following issue: unlike other
zswap backends, zsmalloc performs the LRU list update at the object
mapping time, rather than when the slot for the object is allocated.
This deviation was discussed and agreed upon during the review process
of the zsmalloc writeback patch series:

https://lore.kernel.org/lkml/Y3flcAXNxxrvy3ZH@cmpxchg.org/

Unfortunately, this introduces a subtle bug that occurs when there is a
concurrent store and reclaim, which interleave as follows:

zswap_frontswap_store()            shrink_worker()
  zs_malloc()                        zs_zpool_shrink()
    spin_lock(&pool->lock)             zs_reclaim_page()
    zspage = find_get_zspage()
    spin_unlock(&pool->lock)
                                         spin_lock(&pool->lock)
                                         zspage = list_first_entry(&pool->lru)
                  
---truncated---

## Which versions are affected by CVE-2023-54165?


## How do I fix CVE-2023-54165?

Apply the vendor's patch.

## Is CVE-2023-54165 being exploited?

There is no known exploitation of CVE-2023-54165 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-54165 and fix it if it is affected.

What it is: CVE-2023-54165 is a high-severity vulnerability in Linux, published on 30 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-54165 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-54165/ (Markdown: https://insights.sbomify.com/CVE-2023-54165/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-54165
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-54165
- OSV: https://osv.dev/vulnerability/CVE-2023-54165

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-54165/
Summaries are generated and may contain mistakes; the official description above is the record.