CVE-2023-54042 (GCVE-0-2023-54042)
Vulnerability from cvelistv5 – Published: 2025-12-24 10:56 – Updated: 2026-10-15 21:41
VLAI
EPSS
VEX
Title
powerpc/64s: Fix VAS mm use after free
Summary
In the Linux kernel, the following vulnerability has been resolved:
powerpc/64s: Fix VAS mm use after free
The refcount on mm is dropped before the coprocessor is detached.
Severity
7.8 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-15 21:37 UTC
Assigner
References
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
7bc6f71bdff5f8921e324da0a8fad6f4e2e63a85 , < f7d92313002b2d543500cc417d8079aaed1fb0a8
(git)
Affected: 7bc6f71bdff5f8921e324da0a8fad6f4e2e63a85 , < 4e82f92c349ea603736ade1e814861c0182a55ad (git) Affected: 7bc6f71bdff5f8921e324da0a8fad6f4e2e63a85 , < db8657fdd53c5e3069149d7f957cb60e63027bb2 (git) Affected: 7bc6f71bdff5f8921e324da0a8fad6f4e2e63a85 , < 421cd1544480f2458042fe7f4913a2069c4d7251 (git) Affected: 7bc6f71bdff5f8921e324da0a8fad6f4e2e63a85 , < b4bda59b47879cce38a6ec5a01cd3cac702b5331 (git) |
guessed | |
| Linux | Linux |
Affected:
5.14
Unaffected: 0 , < 5.14 (semver) Unaffected: 5.15.121 , ≤ 5.15.* (semver) Unaffected: 6.1.39 , ≤ 6.1.* (semver) Unaffected: 6.3.13 , ≤ 6.3.* (semver) Unaffected: 6.4.4 , ≤ 6.4.* (semver) Unaffected: 6.5 , ≤ * (original_commit_for_fix) |
guessed |
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"value": "AV:L - The vulnerability is reached through a local character device (`/dev/crypto/nx-gzip`) via `open()` + `ioctl(VAS_TX_WIN_OPEN)` + process exit/`close()`. No network or adjacent-network path exists to the VAS window close path.\nAC:L - The attacker fully controls the trigger: open a window and exit the process, at which point the VAS reference is deterministically the last `mm_count` reference, so `mmdrop()` frees the mm and the immediately following `mm_context_remove_vas_window()` dereferences it. No unwinnable race or uncontrollable precondition is involved, and the sequence can be repeated freely to groom `mm_cachep` reallocation.\nPR:L - Only an unprivileged local account is needed \u2014 there is no `capable()` or `CAP_*` check on any path from the ioctl to `vas_deallocate_window()`/`vas_win_close()`, and `Documentation/powerpc/vas-api.rst` states no special privileges are required to open the nx-gzip device, which is deliberately exposed to ordinary user-space compression libraries.\nUI:N - The attacking process performs every step itself (open, ioctl, exit); no action by another user or administrator is required.\nS:U - The corruption is confined to kernel memory managed by the same kernel security authority; no hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - The freed `mm_struct` is read after free \u2014 `context.id`, `context.copros`, `context.active_cpus`, `mm_users`, and `mm_cpumask()` \u2014 and `mm_cachep` objects are readily reallocated by forking, so the attacker can influence the contents read; a UAF of this kind is leverageable for kernel memory disclosure, and the corrupted TLB-flush scoping can leave stale translations exposing another process\u0027s memory.\nI:H - Multiple writes land in the freed object: `atomic_dec_if_positive()` on `context.copros`/`context.vas_windows`, plus cross-CPU `atomic_dec(\u0026mm-\u003econtext.active_cpus)`, `cpumask_clear_cpu()`, and a possible extra `mmdrop_lazy_tlb()` refcount underflow, giving write primitives into a reallocated live `mm_struct` (or SLUB freelist metadata) that are exploitable for further corruption.\nA:H - The use-after-free reliably corrupts freed slab memory and issues hardware TLB invalidations with a stale PID plus IPIs derived from a freed cpumask, producing oopses, `WARN_ON()` splats (fatal with `panic_on_warn`), slab corruption, and kernel panics \u2014 triggerable repeatedly by any local user."
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"id": "CVE-2023-54042",
"initial_release_date": "2023-01-01T00:00:00+00:00",
"product_status:known_affected": "156",
"product_status:known_not_affected": "118",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: powerpc/64s: Fix VAS mm use after free",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2023/cve-2023-54042.json",
"version": "3"
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| Author | Source | Type | Date | Other |
|---|
Nomenclature
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