FKIE_CVE-2026-93243

Vulnerability from fkie_nvd - Published: 2026-09-24 16:17 - Updated: 2026-09-24 16:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: mm/secretmem: properly account locked pages secretmem accounts folios by treating memory as if it were mlock()'d and thus limited by the RLIMIT_MEMLOCK limit. However the folios are unevictable and remain so until the inode is evicted, eliminating usual mlock() semantics - mapping folios then unmapping them does not clear their unevictable state, since it depends on AS_UNEVICTABLE, not PG_mlocked. A user can therefore easily work around the RLIMIT_MEMLOCK limit - simply map then unmap and VmLck no longer counts the secretmem range. Worse, folios are not accounted in the process's RSS, meaning the OOM killer won't know to kill the process. Repeatedly mapping/unmapping (or forking) can then result in the consumption of all available system memory with unevictable folios and cause system instability. A secretmem fd can be passed between processes and over fork so a per-process limit simply does not make sense, so follow the precedent set by io_uring, perf, skbuff, iommufd and xdp by tracking the number of locked pages in user_struct->locked_vm. Since the scope tracked is actually inode lifetime, the RLIMIT_MEMLOCK applies per-user not per-process, so it doesn't make sense to bypass for users with CAP_IPC_LOCK, therefore remove this bypass. There is simply no reason to carry on marking the mapping as mlock()'d since it's misleading and the lifecycle is now correctly handled, so remove this too. Note that secretmem does not support any form of truncation (including hole punching) and the folios are unreclaimable, so the folios need only be accounted on fault and unaccounted on inode destruction. __secretmem_account_pages() is more or less a duplicate of the code that io_uring etc. use, but since this is a bug fix that needs backporting, defer any de-duplication efforts to a follow-up. test_mlock_limit() asserts mlock_future_ok() on mmap(), however this has been removed, so remove the test altogether for the fix. A new test will be sent separately for upstream.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3b4f72bdddff69819d665395376329ef21f37a06
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/853043cb129473ff2fa0090602be944d96b9d5c9
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/97d34aa65c29cca85e3e9050f4c936389b38a054
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/sched/user.h",
            "mm/secretmem.c",
            "tools/testing/selftests/mm/memfd_secret.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "853043cb129473ff2fa0090602be944d96b9d5c9",
              "status": "affected",
              "version": "1507f51255c9ff07d75909a84e7c0d7f3c4b2f49",
              "versionType": "git"
            },
            {
              "lessThan": "3b4f72bdddff69819d665395376329ef21f37a06",
              "status": "affected",
              "version": "1507f51255c9ff07d75909a84e7c0d7f3c4b2f49",
              "versionType": "git"
            },
            {
              "lessThan": "97d34aa65c29cca85e3e9050f4c936389b38a054",
              "status": "affected",
              "version": "1507f51255c9ff07d75909a84e7c0d7f3c4b2f49",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/linux/sched/user.h",
            "mm/secretmem.c",
            "tools/testing/selftests/mm/memfd_secret.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.14"
            },
            {
              "lessThan": "5.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/secretmem: properly account locked pages\n\nsecretmem accounts folios by treating memory as if it were mlock()\u0027d and\nthus limited by the RLIMIT_MEMLOCK limit.\n\nHowever the folios are unevictable and remain so until the inode is\nevicted, eliminating usual mlock() semantics - mapping folios then\nunmapping them does not clear their unevictable state, since it depends on\nAS_UNEVICTABLE, not PG_mlocked.\n\nA user can therefore easily work around the RLIMIT_MEMLOCK limit - simply\nmap then unmap and VmLck no longer counts the secretmem range.  Worse,\nfolios are not accounted in the process\u0027s RSS, meaning the OOM killer\nwon\u0027t know to kill the process.\n\nRepeatedly mapping/unmapping (or forking) can then result in the\nconsumption of all available system memory with unevictable folios and\ncause system instability.\n\nA secretmem fd can be passed between processes and over fork so a\nper-process limit simply does not make sense, so follow the precedent set\nby io_uring, perf, skbuff, iommufd and xdp by tracking the number of\nlocked pages in user_struct-\u003elocked_vm.\n\nSince the scope tracked is actually inode lifetime, the RLIMIT_MEMLOCK\napplies per-user not per-process, so it doesn\u0027t make sense to bypass for\nusers with CAP_IPC_LOCK, therefore remove this bypass.\n\nThere is simply no reason to carry on marking the mapping as mlock()\u0027d\nsince it\u0027s misleading and the lifecycle is now correctly handled, so\nremove this too.\n\nNote that secretmem does not support any form of truncation (including\nhole punching) and the folios are unreclaimable, so the folios need only\nbe accounted on fault and unaccounted on inode destruction.\n\n__secretmem_account_pages() is more or less a duplicate of the code that\nio_uring etc.  use, but since this is a bug fix that needs backporting,\ndefer any de-duplication efforts to a follow-up.\n\ntest_mlock_limit() asserts mlock_future_ok() on mmap(), however this has\nbeen removed, so remove the test altogether for the fix.  A new test will\nbe sent separately for upstream."
    }
  ],
  "id": "CVE-2026-93243",
  "lastModified": "2026-09-24T16:17:20.230",
  "metrics": {},
  "published": "2026-09-24T16:17:20.230",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3b4f72bdddff69819d665395376329ef21f37a06"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/853043cb129473ff2fa0090602be944d96b9d5c9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/97d34aa65c29cca85e3e9050f4c936389b38a054"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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