{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2025-21727",
  "modified": "2026-10-07T17:22:01Z",
  "upstream": [
    "CVE-2025-21727"
  ],
  "published": "2025-02-27T02:06:37Z",
  "summary": "padata: fix UAF in padata_reorder",
  "details": "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<TASK>\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 'mdelay(10)' is added before calling 'padata_find_next' in the\n'padata_reorder' 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(&pd->refcnt); // 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->pd);\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 'while', if the alg is\ndeleted, the refcnt may be decreased to 0 before entering\n'padata_find_next', 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 'padata_free_shell' 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/",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.129",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2025-21727"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/f78170bee51469734b1a306a74fc5f777bb22ba6"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/f3e0b9f790f8e8065d59e67b565a83154d9f3079"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0ae2f332cfd2d74cf3ce344ec9938cf3e29c3ccd"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/bbccae982e9fa1d7abcb23a5ec81cb0ec883f7de"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/573ac9c70bf7885dc85d82fa44550581bfc3b738"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/80231f069240d52e98b6a317456c67b2eafd0781"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e01780ea4661172734118d2a5f41bc9720765668"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T12:19:11Z"
  }
}