{"api_version":"1","generated_at":"2026-10-24T07:47:17+00:00","cve":"CVE-2025-40199","urls":{"html":"https://cve.report/CVE-2025-40199","api":"https://cve.report/api/cve/CVE-2025-40199.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2025-40199","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2025-40199"},"summary":{"title":"page_pool: Fix PP_MAGIC_MASK to avoid crashing on some 32-bit arches","description":"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 >0, 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's at least 8 bits available and that the PAGE_OFFSET\n  bit calculation doesn't wrap","state":"PUBLISHED","assigner":"Linux","published_at":"2025-11-12 22:15:47","updated_at":"2026-10-19 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Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-40199","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 4f51fb0d257ff4d406ec27966902de075e3b118e 15b8a5b4cdc16e9a8bb2a548e12a0fd92997605a git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ee62ce7a1d909ccba0399680a03c2dee83bcae95 f62934cea32c8f7b11b747975d69bf5afe4264cf git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected ee62ce7a1d909ccba0399680a03c2dee83bcae95 95920c2ed02bde551ab654e9749c2ca7bc3100e0 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected c30ae60f41f9edd6e1b5cad41cf28ce04dae39e4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.12.34 6.12.54 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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 >0, 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's at least 8 bits available and that the PAGE_OFFSET\n  bit calculation doesn't 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 < 0x40000000`) the false positive is deterministic and occurs with no special setup — it fires during boot on stock configuration, and any page-allocation churn reproduces it. No condition beyond the attacker's 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 — 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's own security authority, with no crossing of a VM, IOMMU, or sandbox boundary.\nC:H - A false positive in `netmem_is_pp()` causes `page->mapping` 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->private`-aliased `pp_ref_count`, corrupting page-cache metadata — 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":"2026-10-15T22:02:40.424Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2025-11-12 22:15:47","lastModifiedDate":"2026-10-19 21:10:00","problem_types":[],"metrics":{"cvssMetricV31":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":5.9}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-10-15T21:57:57.920017Z","id":"CVE-2025-40199","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2025","CveId":"40199","Ordinal":"1","Title":"page_pool: Fix PP_MAGIC_MASK to avoid crashing on some 32-bit ar","CVE":"CVE-2025-40199","Year":"2025"},"notes":[{"CveYear":"2025","CveId":"40199","Ordinal":"1","NoteData":"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 >0, 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's at least 8 bits available and that the PAGE_OFFSET\n  bit calculation doesn't wrap","Type":"Description","Title":"page_pool: Fix PP_MAGIC_MASK to avoid crashing on some 32-bit ar"}]}}}