GHSA-7M6P-MVHJ-8V99
Vulnerability from github – Published: 2025-04-16 15:34 – Updated: 2025-10-28 21:30In the Linux kernel, the following vulnerability has been resolved:
mm: zswap: fix crypto_free_acomp() deadlock in zswap_cpu_comp_dead()
Currently, zswap_cpu_comp_dead() calls crypto_free_acomp() while holding the per-CPU acomp_ctx mutex. crypto_free_acomp() then holds scomp_lock (through crypto_exit_scomp_ops_async()).
On the other hand, crypto_alloc_acomp_node() holds the scomp_lock (through crypto_scomp_init_tfm()), and then allocates memory. If the allocation results in reclaim, we may attempt to hold the per-CPU acomp_ctx mutex.
The above dependencies can cause an ABBA deadlock. For example in the following scenario:
(1) Task A running on CPU #1: crypto_alloc_acomp_node() Holds scomp_lock Enters reclaim Reads per_cpu_ptr(pool->acomp_ctx, 1)
(2) Task A is descheduled
(3) CPU #1 goes offline zswap_cpu_comp_dead(CPU #1) Holds per_cpu_ptr(pool->acomp_ctx, 1)) Calls crypto_free_acomp() Waits for scomp_lock
(4) Task A running on CPU #2: Waits for per_cpu_ptr(pool->acomp_ctx, 1) // Read on CPU #1 DEADLOCK
Since there is no requirement to call crypto_free_acomp() with the per-CPU acomp_ctx mutex held in zswap_cpu_comp_dead(), move it after the mutex is unlocked. Also move the acomp_request_free() and kfree() calls for consistency and to avoid any potential sublte locking dependencies in the future.
With this, only setting acomp_ctx fields to NULL occurs with the mutex held. This is similar to how zswap_cpu_comp_prepare() only initializes acomp_ctx fields with the mutex held, after performing all allocations before holding the mutex.
Opportunistically, move the NULL check on acomp_ctx so that it takes place before the mutex dereference.
{
"affected": [],
"aliases": [
"CVE-2025-22030"
],
"database_specific": {
"cwe_ids": [
"CWE-667"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-04-16T15:15:55Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm: zswap: fix crypto_free_acomp() deadlock in zswap_cpu_comp_dead()\n\nCurrently, zswap_cpu_comp_dead() calls crypto_free_acomp() while holding\nthe per-CPU acomp_ctx mutex. crypto_free_acomp() then holds scomp_lock\n(through crypto_exit_scomp_ops_async()).\n\nOn the other hand, crypto_alloc_acomp_node() holds the scomp_lock (through\ncrypto_scomp_init_tfm()), and then allocates memory. If the allocation\nresults in reclaim, we may attempt to hold the per-CPU acomp_ctx mutex.\n\nThe above dependencies can cause an ABBA deadlock. For example in the\nfollowing scenario:\n\n(1) Task A running on CPU #1:\n crypto_alloc_acomp_node()\n Holds scomp_lock\n Enters reclaim\n Reads per_cpu_ptr(pool-\u003eacomp_ctx, 1)\n\n(2) Task A is descheduled\n\n(3) CPU #1 goes offline\n zswap_cpu_comp_dead(CPU #1)\n Holds per_cpu_ptr(pool-\u003eacomp_ctx, 1))\n Calls crypto_free_acomp()\n Waits for scomp_lock\n\n(4) Task A running on CPU #2:\n Waits for per_cpu_ptr(pool-\u003eacomp_ctx, 1) // Read on CPU #1\n DEADLOCK\n\nSince there is no requirement to call crypto_free_acomp() with the per-CPU\nacomp_ctx mutex held in zswap_cpu_comp_dead(), move it after the mutex is\nunlocked. Also move the acomp_request_free() and kfree() calls for\nconsistency and to avoid any potential sublte locking dependencies in the\nfuture.\n\nWith this, only setting acomp_ctx fields to NULL occurs with the mutex\nheld. This is similar to how zswap_cpu_comp_prepare() only initializes\nacomp_ctx fields with the mutex held, after performing all allocations\nbefore holding the mutex.\n\nOpportunistically, move the NULL check on acomp_ctx so that it takes place\nbefore the mutex dereference.",
"id": "GHSA-7m6p-mvhj-8v99",
"modified": "2025-10-28T21:30:29Z",
"published": "2025-04-16T15:34:39Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-22030"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/717d9c35deff6c33235693171bacbb03e9643fa4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/747e3eec1d7d124ea90ed3d7b85369df8b4e36d2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a8d18000e9d2d97aaf105f5f9b3b0e8a6fbf8b96"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c11bcbc0a517acf69282c8225059b2a8ac5fe628"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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