CVE-2025-21919 (GCVE-0-2025-21919)
Vulnerability from cvelistv5
Published
2025-04-01 15:40
Modified
2026-08-05 11:55
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: sched/fair: Fix potential memory corruption in child_cfs_rq_on_list child_cfs_rq_on_list attempts to convert a 'prev' pointer to a cfs_rq. This 'prev' pointer can originate from struct rq's leaf_cfs_rq_list, making the conversion invalid and potentially leading to memory corruption. Depending on the relative positions of leaf_cfs_rq_list and the task group (tg) pointer within the struct, this can cause a memory fault or access garbage data. The issue arises in list_add_leaf_cfs_rq, where both cfs_rq->leaf_cfs_rq_list and rq->leaf_cfs_rq_list are added to the same leaf list. Also, rq->tmp_alone_branch can be set to rq->leaf_cfs_rq_list. This adds a check `if (prev == &rq->leaf_cfs_rq_list)` after the main conditional in child_cfs_rq_on_list. This ensures that the container_of operation will convert a correct cfs_rq struct. This check is sufficient because only cfs_rqs on the same CPU are added to the list, so verifying the 'prev' pointer against the current rq's list head is enough. Fixes a potential memory corruption issue that due to current struct layout might not be manifesting as a crash but could lead to unpredictable behavior when the layout changes.
References
Impacted products
Vendor Product Version
Linux Linux Version: fdaba61ef8a268d4136d0a113d153f7a89eb9984
Version: fdaba61ef8a268d4136d0a113d153f7a89eb9984
Version: fdaba61ef8a268d4136d0a113d153f7a89eb9984
Version: fdaba61ef8a268d4136d0a113d153f7a89eb9984
Version: fdaba61ef8a268d4136d0a113d153f7a89eb9984
Version: fdaba61ef8a268d4136d0a113d153f7a89eb9984
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The attacker\u0027s own workload is sufficient to trigger it.\\nS:U - The bogus pointer arithmetic, out-of-bounds read, and any resulting fault all occur within the kernel\u0027s own security authority on the same host. No VM, IOMMU, or sandbox boundary is crossed.\\nC:H - The type-confused `struct task_group *` is dereferenced at `offsetof(task_group, parent)` from a `list_head` address, which reads out of bounds past the end of the `cfs_rq` slab object into adjacent heap memory whose contents an attacker can influence via heap grooming. This is an unbounded kernel-memory read at an offset determined by struct layout rather than by any bounds check.\\nI:H - This is a genuine type confusion \\u2014 a `struct rq` list head reinterpreted as a member of `struct cfs_rq`, yielding a fabricated object pointer that is dereferenced \\u2014 which upstream explicitly characterizes as \\\"potential memory corruption.\\\" Under differing struct layouts the fabricated `tg` pointer is an arbitrary non-pointer value, so the corrupted access is not confined to a benign read.\\nA:H - The commit states the invalid conversion \\\"can cause a memory fault or access garbage data\\\"; dereferencing a wild `tg` pointer inside the scheduler with the rq lock held produces an oops or panic, and the slab-out-of-bounds read triggers a KASAN report that panics on hardened configurations. A fault in `__update_blocked_fair()` under the runqueue lock is unrecoverable for the affected CPU.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"fdaba61ef8a268d4136d0a113d153f7a89eb9984\", \"lessThan\": \"5cb300dcdd27e6a351ac02541e0231261c775852\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"fdaba61ef8a268d4136d0a113d153f7a89eb9984\", \"lessThan\": \"000c9ee43928f2ce68a156dd40bab7616256f4dd\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"fdaba61ef8a268d4136d0a113d153f7a89eb9984\", \"lessThan\": \"9cc7f0018609f75a349e42e3aebc3b0e905ba775\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"fdaba61ef8a268d4136d0a113d153f7a89eb9984\", \"lessThan\": \"b5741e4b9ef3567613b2351384f91d3f16e59986\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"fdaba61ef8a268d4136d0a113d153f7a89eb9984\", \"lessThan\": \"e1dd09df30ba86716cb2ffab97dc35195c01eb8f\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"fdaba61ef8a268d4136d0a113d153f7a89eb9984\", \"lessThan\": \"3b4035ddbfc8e4521f85569998a7569668cccf51\", \"versionType\": \"git\"}], \"programFiles\": [\"kernel/sched/fair.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"5.13\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"5.13\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"5.15.179\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.15.*\"}, {\"status\": \"unaffected\", \"version\": \"6.1.131\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.1.*\"}, {\"status\": \"unaffected\", \"version\": \"6.6.83\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.12.19\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.12.*\"}, {\"status\": \"unaffected\", \"version\": \"6.13.7\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.13.*\"}, {\"status\": \"unaffected\", \"version\": \"6.14\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"kernel/sched/fair.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/5cb300dcdd27e6a351ac02541e0231261c775852\"}, {\"url\": \"https://git.kernel.org/stable/c/000c9ee43928f2ce68a156dd40bab7616256f4dd\"}, {\"url\": \"https://git.kernel.org/stable/c/9cc7f0018609f75a349e42e3aebc3b0e905ba775\"}, {\"url\": \"https://git.kernel.org/stable/c/b5741e4b9ef3567613b2351384f91d3f16e59986\"}, {\"url\": \"https://git.kernel.org/stable/c/e1dd09df30ba86716cb2ffab97dc35195c01eb8f\"}, {\"url\": \"https://git.kernel.org/stable/c/3b4035ddbfc8e4521f85569998a7569668cccf51\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nsched/fair: Fix potential memory corruption in child_cfs_rq_on_list\\n\\nchild_cfs_rq_on_list attempts to convert a \u0027prev\u0027 pointer to a cfs_rq.\\nThis \u0027prev\u0027 pointer can originate from struct rq\u0027s leaf_cfs_rq_list,\\nmaking the conversion invalid and potentially leading to memory\\ncorruption. Depending on the relative positions of leaf_cfs_rq_list and\\nthe task group (tg) pointer within the struct, this can cause a memory\\nfault or access garbage data.\\n\\nThe issue arises in list_add_leaf_cfs_rq, where both\\ncfs_rq-\u003eleaf_cfs_rq_list and rq-\u003eleaf_cfs_rq_list are added to the same\\nleaf list. Also, rq-\u003etmp_alone_branch can be set to rq-\u003eleaf_cfs_rq_list.\\n\\nThis adds a check `if (prev == \u0026rq-\u003eleaf_cfs_rq_list)` after the main\\nconditional in child_cfs_rq_on_list. This ensures that the container_of\\noperation will convert a correct cfs_rq struct.\\n\\nThis check is sufficient because only cfs_rqs on the same CPU are added\\nto the list, so verifying the \u0027prev\u0027 pointer against the current rq\u0027s list\\nhead is enough.\\n\\nFixes a potential memory corruption issue that due to current struct\\nlayout might not be manifesting as a crash but could lead to unpredictable\\nbehavior when the layout changes.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.15.179\", \"versionStartIncluding\": \"5.13\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.1.131\", \"versionStartIncluding\": \"5.13\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.83\", \"versionStartIncluding\": \"5.13\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12.19\", \"versionStartIncluding\": \"5.13\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.13.7\", \"versionStartIncluding\": \"5.13\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.14\", \"versionStartIncluding\": \"5.13\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-05T11:55:20.805Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2025-21919\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-05T11:55:20.805Z\", \"dateReserved\": \"2024-12-29T08:45:45.787Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2025-04-01T15:40:54.075Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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