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CVE-2025-21727 (GCVE-0-2025-21727)

Vulnerability from cvelistv5 – Published: 2025-02-27 02:07 – Updated: 2026-08-05 11:54
VLAI
Title
padata: fix UAF in padata_reorder
Summary
In the Linux kernel, the following vulnerability has been resolved: padata: fix UAF in padata_reorder A bug was found when run ltp test: BUG: KASAN: slab-use-after-free in padata_find_next+0x29/0x1a0 Read of size 4 at addr ffff88bbfe003524 by task kworker/u113:2/3039206 CPU: 0 PID: 3039206 Comm: kworker/u113:2 Kdump: loaded Not tainted 6.6.0+ Workqueue: pdecrypt_parallel padata_parallel_worker Call Trace: <TASK> dump_stack_lvl+0x32/0x50 print_address_description.constprop.0+0x6b/0x3d0 print_report+0xdd/0x2c0 kasan_report+0xa5/0xd0 padata_find_next+0x29/0x1a0 padata_reorder+0x131/0x220 padata_parallel_worker+0x3d/0xc0 process_one_work+0x2ec/0x5a0 If 'mdelay(10)' is added before calling 'padata_find_next' in the 'padata_reorder' function, this issue could be reproduced easily with ltp test (pcrypt_aead01). This can be explained as bellow: pcrypt_aead_encrypt ... padata_do_parallel refcount_inc(&pd->refcnt); // add refcnt ... padata_do_serial padata_reorder // pd while (1) { padata_find_next(pd, true); // using pd queue_work_on ... padata_serial_worker crypto_del_alg padata_put_pd_cnt // sub refcnt padata_free_shell padata_put_pd(ps->pd); // pd is freed // loop again, but pd is freed // call padata_find_next, UAF } In the padata_reorder function, when it loops in 'while', if the alg is deleted, the refcnt may be decreased to 0 before entering 'padata_find_next', which leads to UAF. As mentioned in [1], do_serial is supposed to be called with BHs disabled and always happen under RCU protection, to address this issue, add synchronize_rcu() in 'padata_free_shell' wait for all _do_serial calls to finish. [1] https://lore.kernel.org/all/20221028160401.cccypv4euxikusiq@parnassus.localdomain/ [2] https://lore.kernel.org/linux-kernel/jfjz5d7zwbytztackem7ibzalm5lnxldi2eofeiczqmqs2m7o6@fq426cwnjtkm/
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-02-27 17:58 UTC
CWE
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: b128a30409356df65f1a51cff3eb986cac8cfedc , < f78170bee51469734b1a306a74fc5f777bb22ba6 (git)
Affected: b128a30409356df65f1a51cff3eb986cac8cfedc , < f3e0b9f790f8e8065d59e67b565a83154d9f3079 (git)
Affected: b128a30409356df65f1a51cff3eb986cac8cfedc , < 0ae2f332cfd2d74cf3ce344ec9938cf3e29c3ccd (git)
Affected: b128a30409356df65f1a51cff3eb986cac8cfedc , < bbccae982e9fa1d7abcb23a5ec81cb0ec883f7de (git)
Affected: b128a30409356df65f1a51cff3eb986cac8cfedc , < 573ac9c70bf7885dc85d82fa44550581bfc3b738 (git)
Affected: b128a30409356df65f1a51cff3eb986cac8cfedc , < 80231f069240d52e98b6a317456c67b2eafd0781 (git)
Affected: b128a30409356df65f1a51cff3eb986cac8cfedc , < e01780ea4661172734118d2a5f41bc9720765668 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.4
Unaffected: 0 , < 5.4 (semver)
Unaffected: 5.10.235 , ≤ 5.10.* (semver)
Unaffected: 5.15.179 , ≤ 5.15.* (semver)
Unaffected: 6.1.129 , ≤ 6.1.* (semver)
Unaffected: 6.6.76 , ≤ 6.6.* (semver)
Unaffected: 6.12.13 , ≤ 6.12.* (semver)
Unaffected: 6.13.2 , ≤ 6.13.* (semver)
Unaffected: 6.14 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem Affected: 0 , < * (custom)
guessed Create a notification for this product.
Show details on NVD website
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\npadata: fix UAF in padata_reorder\n\nA bug was found when run ltp test:\n\nBUG: KASAN: slab-use-after-free in padata_find_next+0x29/0x1a0\nRead of size 4 at addr ffff88bbfe003524 by task kworker/u113:2/3039206\n\nCPU: 0 PID: 3039206 Comm: kworker/u113:2 Kdump: loaded Not tainted 6.6.0+\nWorkqueue: pdecrypt_parallel padata_parallel_worker\nCall Trace:\n\u003cTASK\u003e\ndump_stack_lvl+0x32/0x50\nprint_address_description.constprop.0+0x6b/0x3d0\nprint_report+0xdd/0x2c0\nkasan_report+0xa5/0xd0\npadata_find_next+0x29/0x1a0\npadata_reorder+0x131/0x220\npadata_parallel_worker+0x3d/0xc0\nprocess_one_work+0x2ec/0x5a0\n\nIf \u0027mdelay(10)\u0027 is added before calling \u0027padata_find_next\u0027 in the\n\u0027padata_reorder\u0027 function, this issue could be reproduced easily with\nltp test (pcrypt_aead01).\n\nThis can be explained as bellow:\n\npcrypt_aead_encrypt\n...\npadata_do_parallel\nrefcount_inc(\u0026pd-\u003erefcnt); // add refcnt\n...\npadata_do_serial\npadata_reorder // pd\nwhile (1) {\npadata_find_next(pd, true); // using pd\nqueue_work_on\n...\npadata_serial_worker\t\t\t\tcrypto_del_alg\npadata_put_pd_cnt // sub refcnt\n\t\t\t\t\t\tpadata_free_shell\n\t\t\t\t\t\tpadata_put_pd(ps-\u003epd);\n\t\t\t\t\t\t// pd is freed\n// loop again, but pd is freed\n// call padata_find_next, UAF\n}\n\nIn the padata_reorder function, when it loops in \u0027while\u0027, if the alg is\ndeleted, the refcnt may be decreased to 0 before entering\n\u0027padata_find_next\u0027, which leads to UAF.\n\nAs mentioned in [1], do_serial is supposed to be called with BHs disabled\nand always happen under RCU protection, to address this issue, add\nsynchronize_rcu() in \u0027padata_free_shell\u0027 wait for all _do_serial calls\nto finish.\n\n[1] https://lore.kernel.org/all/20221028160401.cccypv4euxikusiq@parnassus.localdomain/\n[2] https://lore.kernel.org/linux-kernel/jfjz5d7zwbytztackem7ibzalm5lnxldi2eofeiczqmqs2m7o6@fq426cwnjtkm/"
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            "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: padata: correcci\u00f3n de UAF en padata_reorder Se encontr\u00f3 un error al ejecutar la prueba ltp: ERROR: KASAN: slab-use-after-free in padata_find_next+0x29/0x1a0 Read of size 4 at addr ffff88bbfe003524 by task kworker/u113:2/3039206 CPU: 0 PID: 3039206 Comm: kworker/u113:2 Kdump: loaded Not tainted 6.6.0+ Workqueue: pdecrypt_parallel padata_parallel_worker Call Trace:  dump_stack_lvl+0x32/0x50 print_address_description.constprop.0+0x6b/0x3d0 print_report+0xdd/0x2c0 kasan_report+0xa5/0xd0 padata_find_next+0x29/0x1a0 padata_reorder+0x131/0x220 padata_parallel_worker+0x3d/0xc0 process_one_work+0x2ec/0x5a0 If \u0027mdelay(10)\u0027 is added before calling \u0027padata_find_next\u0027 in the \u0027padata_reorder\u0027 function, this issue could be reproduced easily with ltp test (pcrypt_aead01). This can be explained as bellow: pcrypt_aead_encrypt ... padata_do_parallel refcount_inc(\u0026amp;pd-\u0026gt;refcnt); // add refcnt ... padata_do_serial padata_reorder // pd while (1) { padata_find_next(pd, true); // using pd queue_work_on ... padata_serial_worker crypto_del_alg padata_put_pd_cnt // sub refcnt padata_free_shell padata_put_pd(ps-\u0026gt;pd); // pd is freed // loop again, but pd is freed // call padata_find_next, UAF } En la funci\u00f3n padata_reorder, cuando se repite en \u0027while\u0027, si se elimina el alg, el refcnt puede disminuirse a 0 antes de ingresar a \u0027padata_find_next\u0027, lo que lleva a UAF. Como se mencion\u00f3 en [1], se supone que do_serial se debe llamar con los BH deshabilitados y siempre ocurre bajo la protecci\u00f3n de RCU, para abordar este problema, agreguesynchronous_rcu() en \u0027padata_free_shell\u0027 y espere a que finalicen todas las llamadas a _do_serial. [1] https://lore.kernel.org/all/20221028160401.cccypv4euxikusiq@parnassus.localdomain/ [2] https://lore.kernel.org/linux-kernel/jfjz5d7zwbytztackem7ibzalm5lnxldi2eofeiczqmqs2m7o6@fq426cwnjtkm/"
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              "value": "In the Linux kernel, the following vulnerability has been resolved:\n\npadata: fix UAF in padata_reorder\n\nA bug was found when run ltp test:\n\nBUG: KASAN: slab-use-after-free in padata_find_next+0x29/0x1a0\nRead of size 4 at addr ffff88bbfe003524 by task kworker/u113:2/3039206\n\nCPU: 0 PID: 3039206 Comm: kworker/u113:2 Kdump: loaded Not tainted 6.6.0+\nWorkqueue: pdecrypt_parallel padata_parallel_worker\nCall Trace:\n\u003cTASK\u003e\ndump_stack_lvl+0x32/0x50\nprint_address_description.constprop.0+0x6b/0x3d0\nprint_report+0xdd/0x2c0\nkasan_report+0xa5/0xd0\npadata_find_next+0x29/0x1a0\npadata_reorder+0x131/0x220\npadata_parallel_worker+0x3d/0xc0\nprocess_one_work+0x2ec/0x5a0\n\nIf \u0027mdelay(10)\u0027 is added before calling \u0027padata_find_next\u0027 in the\n\u0027padata_reorder\u0027 function, this issue could be reproduced easily with\nltp test (pcrypt_aead01).\n\nThis can be explained as bellow:\n\npcrypt_aead_encrypt\n...\npadata_do_parallel\nrefcount_inc(\u0026pd-\u003erefcnt); // add refcnt\n...\npadata_do_serial\npadata_reorder // pd\nwhile (1) {\npadata_find_next(pd, true); // using pd\nqueue_work_on\n...\npadata_serial_worker\t\t\t\tcrypto_del_alg\npadata_put_pd_cnt // sub refcnt\n\t\t\t\t\t\tpadata_free_shell\n\t\t\t\t\t\tpadata_put_pd(ps-\u003epd);\n\t\t\t\t\t\t// pd is freed\n// loop again, but pd is freed\n// call padata_find_next, UAF\n}\n\nIn the padata_reorder function, when it loops in \u0027while\u0027, if the alg is\ndeleted, the refcnt may be decreased to 0 before entering\n\u0027padata_find_next\u0027, which leads to UAF.\n\nAs mentioned in [1], do_serial is supposed to be called with BHs disabled\nand always happen under RCU protection, to address this issue, add\nsynchronize_rcu() in \u0027padata_free_shell\u0027 wait for all _do_serial calls\nto finish.\n\n[1] https://lore.kernel.org/all/20221028160401.cccypv4euxikusiq@parnassus.localdomain/\n[2] https://lore.kernel.org/linux-kernel/jfjz5d7zwbytztackem7ibzalm5lnxldi2eofeiczqmqs2m7o6@fq426cwnjtkm/"
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
              },
              "scenarios": [
                {
                  "lang": "en",
                  "value": "AV:L - The vulnerable padata/pcrypt path is driven through local syscalls \u2014 an AF_ALG socket bound to `pcrypt(...)` submitting aead requests, and the racing teardown via crypto module autoload or the NETLINK_CRYPTO socket. No remote peer can reach or free the padata shell on its own.\nAC:L - The attacker controls both sides of the race: they flood concurrent pcrypt requests to keep `padata_reorder()` spinning in its loop while triggering instance teardown, and can widen the window with CPU contention and many parallel workers. The commit confirms it reproduces with a stock LTP test (pcrypt_aead01) once the loop is delayed, meaning it is a naturally occurring, repeatable window.\nPR:L - A basic unprivileged local user can both instantiate and continuously drive pcrypt via AF_ALG (`alg_bind` performs no capability check) and trigger the teardown side, since `crypto_alg_finish_registration()` \u2192 `crypto_remove_spawns()` destroys the pcrypt instance when an equal-or-higher-priority same-named implementation registers \u2014 a module autoload reachable from the same unprivileged bind path.\nUI:N - Exploitation is entirely attacker-driven through socket operations and crypto requests; no victim action, mount, or file open is required.\nS:U - The use-after-free corrupts kernel slab memory and stays within the kernel\u0027s own security authority; there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - Reclaiming the freed `struct parallel_data` gives the attacker control of `pd-\u003ereorder_list`, whose per-CPU dereference in `padata_find_next()` becomes an attacker-directed kernel read, and `pd-\u003eps-\u003epinst` is likewise dereferenced \u2014 yielding disclosure of arbitrary kernel memory.\nI:H - The same UAF provides write primitives \u2014 `list_del_init()` unlink on an attacker-controlled reorder list, `++pd-\u003eprocessed` / `pd-\u003ecpu` writes, and most severely `queue_work(pinst-\u003eserial_wq, \u0026pd-\u003ereorder_work)` invoking a function pointer living in freed, sprayable memory, enabling control-flow hijack and privilege escalation.\nA:H - Even unweaponized, the slab-use-after-free reported by KASAN dereferences freed percpu and workqueue pointers from a kworker context, reliably producing an oops or kernel panic and taking the system down."
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-08-05T11:54:00.224Z",
            "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "shortName": "Linux"
          },
          "references": [
            {
              "url": "https://git.kernel.org/stable/c/f78170bee51469734b1a306a74fc5f777bb22ba6"
            },
            {
              "url": "https://git.kernel.org/stable/c/f3e0b9f790f8e8065d59e67b565a83154d9f3079"
            },
            {
              "url": "https://git.kernel.org/stable/c/0ae2f332cfd2d74cf3ce344ec9938cf3e29c3ccd"
            },
            {
              "url": "https://git.kernel.org/stable/c/bbccae982e9fa1d7abcb23a5ec81cb0ec883f7de"
            },
            {
              "url": "https://git.kernel.org/stable/c/573ac9c70bf7885dc85d82fa44550581bfc3b738"
            },
            {
              "url": "https://git.kernel.org/stable/c/80231f069240d52e98b6a317456c67b2eafd0781"
            },
            {
              "url": "https://git.kernel.org/stable/c/e01780ea4661172734118d2a5f41bc9720765668"
            }
          ],
          "title": "padata: fix UAF in padata_reorder",
          "x_generator": {
            "engine": "bippy-1.2.0"
          }
        }
      },
      "cveMetadata": {
        "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "assignerShortName": "Linux",
        "cveId": "CVE-2025-21727",
        "datePublished": "2025-02-27T02:07:33.501Z",
        "dateReserved": "2024-12-29T08:45:45.754Z",
        "dateUpdated": "2026-08-05T11:54:00.224Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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