tcp: TX zerocopy should not sense pfmemalloc status

{
  "id": "eba969d1a2cd8dd321b2bce1d31aa37d5c26b0f560478db9e6968c460ac3c06e",
  "url": "https://osv.dev/vulnerability/CVE-2022-48689",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "tcp: TX zerocopy should not sense pfmemalloc status",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: tcp: TX zerocopy should not sense pfmemalloc status We got a recent syzbot report [1] showing a possible misuse of pfmemalloc page status in TCP zerocopy paths. Indeed, for pages coming from user space or other layers, using page_is_pfmemalloc() is moot, and possibly could give false positives. There has been attempts to make page_is_pfmemalloc() more robust, but not using it in the first place in this context is probably better, removing cpu cycles. Note to stable teams : You need to backport 84ce071e38a6 (\"net: introduce __skb_fill_page_desc_noacc\") as a prereq. Race is more probable after commit c07aea3ef4d4 (\"mm: add a signature in struct page\") because page_is_pfmemalloc() is now using low order bit from page->lru.next, which can change more often than page->index. Low order bit should never be set for lru.next (when used as an anchor in LRU list), so KCSAN report is mostly a false positive. Backporting to older kernel versions seems not necessary. [1] BUG: KCSAN: data-race in lru_add_fn / tcp_build_frag write to 0xffffea0004a1d2c8 of 8 bytes by task 18600 on cpu 0: __list_add include/linux/list.h:73 [inline] list_add include/linux/list.h:88 [inline] lruvec_add_folio include/linux/mm_inline.h:105 [inline] lru_add_fn+0x440/0x520 mm/swap.c:228 folio_batch_move_lru+0x1e1/0x2a0 mm/swap.c:246 folio_batch_add_and_move mm/swap.c:263 [inline] folio_add_lru+0xf1/0x140 mm/swap.c:490 filemap_add_folio+0xf8/0x150 mm",
    "evidence": "osv:CVE-2022-48689",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.15.68",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.19.9",
            "evidence": "/affected/1/ranges"
          }
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        "affected_versions": []
      }
    ],
    "severity": "medium",
    "structured": {
      "id": "CVE-2022-48689",
      "aliases": [
        "CVE-2022-48689"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L"
        }
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      "affected": [
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              "type": "GIT",
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                {
                  "fixed": "8527c9a6bf8e54fef0a8d3d7d8874a48c725c915"
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                {
                  "fixed": "6730c48ed6b0cd939fc9b30b2d621ce0b89bea83"
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              "type": "ECOSYSTEM",
              "events": [
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                  "introduced": "5.14.0"
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              "type": "ECOSYSTEM",
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          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-48689.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:23.931293768Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/3261400639463a853ba2b3be8bd009c2a8089775",
        "https://git.kernel.org/stable/c/6730c48ed6b0cd939fc9b30b2d621ce0b89bea83",
        "https://git.kernel.org/stable/c/8527c9a6bf8e54fef0a8d3d7d8874a48c725c915",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/48xxx/CVE-2022-48689.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2022-48689",
        "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/2022/48xxx/CVE-2022-48689.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2022-48689",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 490324,
  "published_at": "2024-05-03T15:00:02.083+00:00"
}