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CVE-2025-40199 (GCVE-0-2025-40199)

Vulnerability from cvelistv5 – Published: 2025-11-12 21:56 – Updated: 2026-08-05 12:08
VLAI
Title
page_pool: Fix PP_MAGIC_MASK to avoid crashing on some 32-bit arches
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
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 4f51fb0d257ff4d406ec27966902de075e3b118e , < 15b8a5b4cdc16e9a8bb2a548e12a0fd92997605a (git)
Affected: ee62ce7a1d909ccba0399680a03c2dee83bcae95 , < f62934cea32c8f7b11b747975d69bf5afe4264cf (git)
Affected: ee62ce7a1d909ccba0399680a03c2dee83bcae95 , < 95920c2ed02bde551ab654e9749c2ca7bc3100e0 (git)
Affected: c30ae60f41f9edd6e1b5cad41cf28ce04dae39e4 (git)
Affected: 6.12.34 , < 6.12.54 (semver)
Affected: 6.15.3 , < 6.16 (semver)
guessed Create a notification for this product.
Linux Linux Affected: 6.16
Unaffected: 0 , < 6.16 (semver)
Unaffected: 6.12.54 , ≤ 6.12.* (semver)
Unaffected: 6.17.4 , ≤ 6.17.* (semver)
Unaffected: 6.18 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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          "product": "Linux",
          "programFiles": [
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                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.17.4",
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                  "vulnerable": true
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          "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"
        }
      ],
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        {
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            "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"
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              "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."
            }
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    "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"
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            "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"
          }
        ],
        "id": "CVE-2025-40199",
        "lastModified": "2026-07-30T06:24:17.120",
        "metrics": {
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            {
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                "attackComplexity": "LOW",
                "attackVector": "LOCAL",
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                "baseScore": 7.8,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "LOW",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "published": "2025-11-12T22:15:47.043",
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          {
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            "url": "https://git.kernel.org/stable/c/15b8a5b4cdc16e9a8bb2a548e12a0fd92997605a"
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      "current_release_date": "2026-07-30T08:47:28+00:00",
      "cve": "CVE-2025-40199",
      "id": "CVE-2025-40199",
      "initial_release_date": "2025-11-12T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: page_pool: Fix PP_MAGIC_MASK to avoid crashing on some 32-bit arches",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-40199.json",
      "version": "3"
    }
  }
}



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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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