netfs: Fix missing alloc tagging of direct mempool allocations

{
  "id": "6632d481b225616afa59e80d94707640e493a5a229072b32ba4b1aa93cb39ba9",
  "url": "https://osv.dev/vulnerability/CVE-2026-98920",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "netfs: Fix missing alloc tagging of direct mempool allocations",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: netfs: Fix missing alloc tagging of direct mempool allocations Commit 1d78d56c43ef (\"netfs: Fix folio_queue ENOMEM in writeback by adding a mempool\") added a mempool for the folio_queues and made the request, subrequest and folio_queue allocations distinguish between writeback and everything else. Writeback is part of memory reclaim and must not fail due to ENOMEM, so it allocates under GFP_NOFS through mempool_alloc(), which may dip into the pool's reserve and, if that runs empty, wait for elements to be returned. The GFP_KERNEL paths, which can return -ENOMEM to their callers, invoke the pool's ->alloc() callback directly instead. The direct call, however, skips the alloc_hooks() wrapper that the mempool_alloc() macro provides. The pool callbacks, mempool_alloc_slab() and mempool_kmalloc(), call kmem_cache_alloc_noprof() and kmalloc_noprof() and rely on current->alloc_tag having been set by the caller. With CONFIG_MEM_ALLOC_PROFILING_DEBUG=y this leads to current->alloc_tag not set WARNING: ./include/linux/alloc_tag.h:161 at __alloc_tagging_slab_alloc_hook alloc_tag was not set WARNING: ./include/linux/alloc_tag.h:166 at __alloc_tagging_slab_free_hook at allocation and free time respectively, as reported when reading files on a CIFS mount. The allocations are also missing from /proc/allocinfo. Wrap the direct ->alloc() invocations in alloc_hooks() with a new mempool_alloc_noreserve() helper in include/linux",
    "evidence": "osv:CVE-2026-98920",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "7.2.9",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-98920",
      "aliases": [
        "CVE-2026-98920"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
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                  "fixed": "5c03da745171485fd181f17b69213464f6d05f3d"
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                {
                  "fixed": "37a2042748bc880df03ff8315db86ed82991fbb8"
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                {
                  "fixed": "b78b728e21c32ec4c330b299f657fb1eb02dffc2"
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            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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          "versions": [
            "v6.12.114",
            "v7.1.13",
            "v7.1.12",
            "v7.1.11",
            "v7.1.10",
            "v7.1.9",
            "v7.1.8"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98920.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "7.2.0"
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                {
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          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98920.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:30.329340649Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/37a2042748bc880df03ff8315db86ed82991fbb8",
        "https://git.kernel.org/stable/c/5c03da745171485fd181f17b69213464f6d05f3d",
        "https://git.kernel.org/stable/c/b78b728e21c32ec4c330b299f657fb1eb02dffc2",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98920.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-98920",
        "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/2026/98xxx/CVE-2026-98920.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-98920",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 497330,
  "published_at": "2026-10-23T12:02:06.56+00:00"
}