list: fix a data-race around ep->rdllist

{
  "id": "af5dd4601dc4c76a550661993be1ce266cc95e4889471ec0e1c6fc6f0d4effab",
  "url": "https://osv.dev/vulnerability/CVE-2022-49443",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "list: fix a data-race around ep->rdllist",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: list: fix a data-race around ep->rdllist ep_poll() first calls ep_events_available() with no lock held and checks if ep->rdllist is empty by list_empty_careful(), which reads rdllist->prev. Thus all accesses to it need some protection to avoid store/load-tearing. Note INIT_LIST_HEAD_RCU() already has the annotation for both prev and next. Commit bf3b9f6372c4 (\"epoll: Add busy poll support to epoll with socket fds.\") added the first lockless ep_events_available(), and commit c5a282e9635e (\"fs/epoll: reduce the scope of wq lock in epoll_wait()\") made some ep_events_available() calls lockless and added single call under a lock, finally commit e59d3c64cba6 (\"epoll: eliminate unnecessary lock for zero timeout\") made the last ep_events_available() lockless. BUG: KCSAN: data-race in do_epoll_wait / do_epoll_wait write to 0xffff88810480c7d8 of 8 bytes by task 1802 on cpu 0: INIT_LIST_HEAD include/linux/list.h:38 [inline] list_splice_init include/linux/list.h:492 [inline] ep_start_scan fs/eventpoll.c:622 [inline] ep_send_events fs/eventpoll.c:1656 [inline] ep_poll fs/eventpoll.c:1806 [inline] do_epoll_wait+0x4eb/0xf40 fs/eventpoll.c:2234 do_epoll_pwait fs/eventpoll.c:2268 [inline] __do_sys_epoll_pwait fs/eventpoll.c:2281 [inline] __se_sys_epoll_pwait+0x12b/0x240 fs/eventpoll.c:2275 __x64_sys_epoll_pwait+0x74/0x80 fs/eventpoll.c:2275 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/en",
    "evidence": "osv:CVE-2022-49443",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.15.46",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.17.14",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.18.3",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CVE-2022-49443",
      "aliases": [
        "CVE-2022-49443"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "bf3b9f6372c45b0fbf24d86b8794910d20170017"
                },
                {
                  "fixed": "5d5d993f16be15d124be7b8ec71b28ef7b7dc3af"
                },
                {
                  "fixed": "cb3e48f7a35033deb9455abe3932e63cb500b9eb"
                },
                {
                  "fixed": "e039c0b5985999b150594126225e1ee51df7b4c9"
                },
                {
                  "fixed": "d679ae94fdd5d3ab00c35078f5af5f37e068b03d"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49443.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "4.12.0"
                },
                {
                  "fixed": "5.15.46"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "5.17.14"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.18.0"
                },
                {
                  "fixed": "5.18.3"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49443.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:28.743881484Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/5d5d993f16be15d124be7b8ec71b28ef7b7dc3af",
        "https://git.kernel.org/stable/c/cb3e48f7a35033deb9455abe3932e63cb500b9eb",
        "https://git.kernel.org/stable/c/d679ae94fdd5d3ab00c35078f5af5f37e068b03d",
        "https://git.kernel.org/stable/c/e039c0b5985999b150594126225e1ee51df7b4c9",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49443.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2022-49443",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49443.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2022-49443",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 495043,
  "published_at": "2025-02-26T02:12:55.959+00:00"
}