CVE-2025-40199 (GCVE-0-2025-40199)
Vulnerability from cvelistv5
Published
2025-11-12 21:56
Modified
2026-08-05 12:08
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: page_pool: Fix PP_MAGIC_MASK to avoid crashing on some 32-bit arches Helge reported that the introduction of PP_MAGIC_MASK let to crashes on boot on his 32-bit parisc machine. The cause of this is the mask is set too wide, so the page_pool_page_is_pp() incurs false positives which crashes the machine. Just disabling the check in page_pool_is_pp() will lead to the page_pool code itself malfunctioning; so instead of doing this, this patch changes the define for PP_DMA_INDEX_BITS to avoid mistaking arbitrary kernel pointers for page_pool-tagged pages. The fix relies on the kernel pointers that alias with the pp_magic field always being above PAGE_OFFSET. With this assumption, we can use the lowest bit of the value of PAGE_OFFSET as the upper bound of the PP_DMA_INDEX_MASK, which should avoid the false positives. Because we cannot rely on PAGE_OFFSET always being a compile-time constant, nor on it always being >0, we fall back to disabling the dma_index storage when there are not enough bits available. This leaves us in the situation we were in before the patch in the Fixes tag, but only on a subset of architecture configurations. This seems to be the best we can do until the transition to page types in complete for page_pool pages. v2: - Make sure there's at least 8 bits available and that the PAGE_OFFSET bit calculation doesn't wrap
References
Impacted products
Vendor Product Version
Linux Linux Version: 4f51fb0d257ff4d406ec27966902de075e3b118e
Version: ee62ce7a1d909ccba0399680a03c2dee83bcae95
Version: ee62ce7a1d909ccba0399680a03c2dee83bcae95
Version: c30ae60f41f9edd6e1b5cad41cf28ce04dae39e4
Version: 6.12.34   ≤
Version: 6.15.3   ≤
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/mm.h",
            "net/core/page_pool.c"
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            "net/core/page_pool.c"
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              "version": "6.17.4",
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              "status": "unaffected",
              "version": "6.18",
              "versionType": "original_commit_for_fix"
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      ],
      "cpeApplicability": [
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          "nodes": [
            {
              "cpeMatch": [
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                  "vulnerable": true
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              "negate": false,
              "operator": "OR"
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        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\npage_pool: Fix PP_MAGIC_MASK to avoid crashing on some 32-bit arches\n\nHelge reported that the introduction of PP_MAGIC_MASK let to crashes on\nboot on his 32-bit parisc machine. The cause of this is the mask is set\ntoo wide, so the page_pool_page_is_pp() incurs false positives which\ncrashes the machine.\n\nJust disabling the check in page_pool_is_pp() will lead to the page_pool\ncode itself malfunctioning; so instead of doing this, this patch changes\nthe define for PP_DMA_INDEX_BITS to avoid mistaking arbitrary kernel\npointers for page_pool-tagged pages.\n\nThe fix relies on the kernel pointers that alias with the pp_magic field\nalways being above PAGE_OFFSET. With this assumption, we can use the\nlowest bit of the value of PAGE_OFFSET as the upper bound of the\nPP_DMA_INDEX_MASK, which should avoid the false positives.\n\nBecause we cannot rely on PAGE_OFFSET always being a compile-time\nconstant, nor on it always being \u003e0, we fall back to disabling the\ndma_index storage when there are not enough bits available. This leaves\nus in the situation we were in before the patch in the Fixes tag, but\nonly on a subset of architecture configurations. This seems to be the\nbest we can do until the transition to page types in complete for\npage_pool pages.\n\nv2:\n- Make sure there\u0027s at least 8 bits available and that the PAGE_OFFSET\n  bit calculation doesn\u0027t wrap"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The broken `PP_MAGIC_MASK` is evaluated on every page free/alloc check and on every page_pool skb recycle, driven by ordinary local memory and I/O activity rather than by attacker-supplied packet content; an unprivileged local process reliably reaches `free_page_is_bad()`/`napi_pp_put_page()` through normal slab and socket buffer churn. No remote input influences the aliased pointer values, so Local is the accurate vector.\nAC:L - On an affected architecture (32-bit parisc/m68k/nommu targets whose default `PAGE_OFFSET \u003c 0x40000000`) the false positive is deterministic and occurs with no special setup \u2014 it fires during boot on stock configuration, and any page-allocation churn reproduces it. No condition beyond the attacker\u0027s control is required.\nPR:L - Any unprivileged local user can drive slab page frees and network buffer recycling that funnel pages through `page_pool_page_is_pp()`/`netmem_is_pp()`; no capability, namespace privilege, or root is needed. The condition even manifests spontaneously under the init process during boot.\nUI:N - No victim action is required \u2014 the misidentification happens inside the page allocator and skb free paths during normal kernel operation.\nS:U - Both the flawed check and its consequences (page allocator state, page_pool/skb handling) live entirely within the kernel\u0027s own security authority, with no crossing of a VM, IOMMU, or sandbox boundary.\nC:H - A false positive in `netmem_is_pp()` causes `page-\u003emapping` to be reinterpreted as a `struct page_pool *` and dereferenced throughout `page_pool_put_unrefed_netmem()`, giving a type-confusion read primitive over arbitrary kernel memory; `bad_page()` additionally dumps raw `struct page` contents and kernel pointers to the log.\nI:H - The same type confusion lets `page_pool_recycle_in_cache()`/`page_pool_recycle_in_ring()` write netmem values and update counters at offsets from an uncontrolled kernel pointer, and `skb_pp_frag_ref()` performs `atomic_long_inc()` on the `page-\u003eprivate`-aliased `pp_ref_count`, corrupting page-cache metadata \u2014 memory corruption leverageable for control-flow hijack.\nA:H - The reported symptom is a machine crash on boot: every affected slab page free triggers a \"BUG: Bad page state ... page_pool leak\" splat and permanently leaks the page, exhausting memory, while the network path oopses on a wild `page_pool` pointer dereference."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:08:28.841Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/15b8a5b4cdc16e9a8bb2a548e12a0fd92997605a"
        },
        {
          "url": "https://git.kernel.org/stable/c/f62934cea32c8f7b11b747975d69bf5afe4264cf"
        },
        {
          "url": "https://git.kernel.org/stable/c/95920c2ed02bde551ab654e9749c2ca7bc3100e0"
        }
      ],
      "title": "page_pool: Fix PP_MAGIC_MASK to avoid crashing on some 32-bit arches",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-40199",
    "datePublished": "2025-11-12T21:56:33.510Z",
    "dateReserved": "2025-04-16T07:20:57.178Z",
    "dateUpdated": "2026-08-05T12:08:28.841Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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