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linux — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2023-53728

In the Linux kernel, the following vulnerability has been resolved: posix-timers: Ensure timer ID search-loop limit is valid posix_timer_add() tries to allocate a posix timer ID by starting from the cached ID which was stored by the last successful allocation. This is done in a loop searching the ID space for a free slot one by one. The loop has to terminate when the search wrapped around to the starting point. But that's racy vs. establishing the starting point. That is read out lockless, which leads to the following problem: CPU0 CPU1 posix_timer_add() start = sig->posix_timer_id; lock(hash_lock); ... posix_timer_add() if (++sig->posix_timer_id < 0) start = sig->posix_timer_id; sig->posix_timer_id = 0; So CPU1 can observe a negative start value, i.e. -1, and the loop break never happens because the condition can never be true: if (sig->posix_timer_id == start) break; While this is unlikely to ever turn into an endless loop as the ID space is huge (INT_MAX), the racy read of the start value caught the attention of KCSAN and Dmitry unearthed that incorrectness. Rewrite it so that all id operations are under the hash lock.

Products: linux
Affected versions: 6.1.106-1, 6.1.106-2, 6.1.106-3, 6.1.27-1, 6.1.37-1, 6.1.38-1, 6.1.38-2, 6.1.38-2~bpo11+1, 6.1.38-3, 6.1.38-4, 6.1.38-4~bpo11+1, 6.1.52-1, 6.1.55-1, 6.1.55-1~bpo11+1, 6.1.64-1, 6.1.66-1, 6.1.67-1, 6.1.69-1, 6.1.69-1~bpo11+1, 6.1.76-1, 6.1.76-1~bpo11+1, 6.1.82-1, 6.1.85-1, 6.1.90-1, 6.1.90-1~bpo11+1, 6.1.94-1, 6.1.94-1~bpo11+1, 6.1.98-1, 6.1.99-1
Fixed versions: 6.1.112-1, 6.4.11-1
CVEs: CVE-2023-53728
Confirmed fixed CVEs: Not specified
Updated in this feed: 1 Nov 2026, 15:14 UTC · Revision 1

Source evidence

DEBIAN-CVE-2023-53728

core-osv · Original source

Published 22 Oct 2025, 14:15 UTC

osv:DEBIAN-CVE-2023-53728

linux

Fixed versions: 6.1.112-1

linux

Fixed versions: 6.4.11-1

linux

Fixed versions: 6.4.11-1

Complete source record

{
  "id": "27aeedea679b2533a6d39b455c46f934d1544af33547109ffe9aa48a703bd30a",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2023-53728",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2023-53728",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: posix-timers: Ensure timer ID search-loop limit is valid posix_timer_add() tries to allocate a posix timer ID by starting from the cached ID which was stored by the last successful allocation. This is done in a loop searching the ID space for a free slot one by one. The loop has to terminate when the search wrapped around to the starting point. But that's racy vs. establishing the starting point. That is read out lockless, which leads to the following problem: CPU0 CPU1 posix_timer_add() start = sig->posix_timer_id; lock(hash_lock); ... posix_timer_add() if (++sig->posix_timer_id < 0) start = sig->posix_timer_id; sig->posix_timer_id = 0; So CPU1 can observe a negative start value, i.e. -1, and the loop break never happens because the condition can never be true: if (sig->posix_timer_id == start) break; While this is unlikely to ever turn into an endless loop as the ID space is huge (INT_MAX), the racy read of the start value caught the attention of KCSAN and Dmitry unearthed that incorrectness. Rewrite it so that all id operations are under the hash lock.",
    "evidence": "osv:DEBIAN-CVE-2023-53728",
    "products": [
      {
        "name": {
          "value": "linux",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.1.112-1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": [
          {
            "value": "6.1.106-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.106-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.106-3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.27-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.37-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.38-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.38-2",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.38-2~bpo11+1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.38-3",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.38-4",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.38-4~bpo11+1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.52-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.55-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.55-1~bpo11+1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.64-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.66-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.67-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.69-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.69-1~bpo11+1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.76-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.76-1~bpo11+1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.82-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.85-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.90-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.90-1~bpo11+1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.94-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.94-1~bpo11+1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.98-1",
            "evidence": "/affected/0/versions"
          },
          {
            "value": "6.1.99-1",
            "evidence": "/affected/0/versions"
          }
        ]
      },
      {
        "name": {
          "value": "linux",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.4.11-1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "linux",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "6.4.11-1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "DEBIAN-CVE-2023-53728",
      "aliases": [
        "DEBIAN-CVE-2023-53728"
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "6.1.112-1"
                }
              ]
            }
          ],
          "package": {
            "name": "linux",
            "purl": "pkg:deb/debian/linux?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "versions": [
            "6.1.106-1",
            "6.1.106-2",
            "6.1.106-3",
            "6.1.27-1",
            "6.1.37-1",
            "6.1.38-1",
            "6.1.38-2",
            "6.1.38-2~bpo11+1",
            "6.1.38-3",
            "6.1.38-4",
            "6.1.38-4~bpo11+1",
            "6.1.52-1",
            "6.1.55-1",
            "6.1.55-1~bpo11+1",
            "6.1.64-1",
            "6.1.66-1",
            "6.1.67-1",
            "6.1.69-1",
            "6.1.69-1~bpo11+1",
            "6.1.76-1",
            "6.1.76-1~bpo11+1",
            "6.1.82-1",
            "6.1.85-1",
            "6.1.90-1",
            "6.1.90-1~bpo11+1",
            "6.1.94-1",
            "6.1.94-1~bpo11+1",
            "6.1.98-1",
            "6.1.99-1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-53728.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "6.4.11-1"
                }
              ]
            }
          ],
          "package": {
            "name": "linux",
            "purl": "pkg:deb/debian/linux?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-53728.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "6.4.11-1"
                }
              ]
            }
          ],
          "package": {
            "name": "linux",
            "purl": "pkg:deb/debian/linux?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2023-53728.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-26T17:47:40.810681340Z",
      "provider": "osv",
      "upstream": [
        "CVE-2023-53728"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2023-53728"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2023-53728",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 454801,
  "published_at": "2025-10-22T14:15:48.083+00:00"
}