{"dataType": "CVE_RECORD", "dataVersion": "5.1", "cveMetadata": {"cveId": "CVE-2025-38434", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T04:51:24.015Z", "datePublished": "2025-07-25T14:32:08.089Z", "dateUpdated": "2025-07-28T04:22:07.336Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2025-07-28T04:22:07.336Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRevert \"riscv: Define TASK_SIZE_MAX for __access_ok()\"\n\nThis reverts commit ad5643cf2f69 (\"riscv: Define TASK_SIZE_MAX for\n__access_ok()\").\n\nThis commit changes TASK_SIZE_MAX to be LONG_MAX to optimize access_ok(),\nbecause the previous TASK_SIZE_MAX (default to TASK_SIZE) requires some\ncomputation.\n\nThe reasoning was that all user addresses are less than LONG_MAX, and all\nkernel addresses are greater than LONG_MAX. Therefore access_ok() can\nfilter kernel addresses.\n\nAddresses between TASK_SIZE and LONG_MAX are not valid user addresses, but\naccess_ok() let them pass. That was thought to be okay, because they are\nnot valid addresses at hardware level.\n\nUnfortunately, one case is missed: get_user_pages_fast() happily accepts\naddresses between TASK_SIZE and LONG_MAX. futex(), for instance, uses\nget_user_pages_fast(). This causes the problem reported by Robert [1].\n\nTherefore, revert this commit. TASK_SIZE_MAX is changed to the default:\nTASK_SIZE.\n\nThis unfortunately reduces performance, because TASK_SIZE is more expensive\nto compute compared to LONG_MAX. But correctness first, we can think about\noptimization later, if required."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/riscv/include/asm/pgtable.h"], "versions": [{"version": "ad5643cf2f699989daa85d909403febd6712fccb", "lessThan": "fe30c30bf3bb68d4a4d8c7c814769857b5c973e6", "status": "affected", "versionType": "git"}, {"version": "ad5643cf2f699989daa85d909403febd6712fccb", "lessThan": "f8b1898748dfeb4f9b67b6a6d661f354b9de3523", "status": "affected", "versionType": "git"}, {"version": "ad5643cf2f699989daa85d909403febd6712fccb", "lessThan": "890ba5be6335dbbbc99af14ea007befb5f83f174", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["arch/riscv/include/asm/pgtable.h"], "versions": [{"version": "6.10", "status": "affected"}, {"version": "0", "lessThan": "6.10", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.36", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.15.5", "lessThanOrEqual": "6.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.16", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "6.12.36"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "6.15.5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "6.16"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/fe30c30bf3bb68d4a4d8c7c814769857b5c973e6"}, {"url": "https://git.kernel.org/stable/c/f8b1898748dfeb4f9b67b6a6d661f354b9de3523"}, {"url": "https://git.kernel.org/stable/c/890ba5be6335dbbbc99af14ea007befb5f83f174"}], "title": "Revert \"riscv: Define TASK_SIZE_MAX for __access_ok()\"", "x_generator": {"engine": "bippy-1.2.0"}}}}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRevert \"riscv: Define TASK_SIZE_MAX for __access_ok()\"\n\nThis reverts commit ad5643cf2f69 (\"riscv: Define TASK_SIZE_MAX for\n__access_ok()\").\n\nThis commit changes TASK_SIZE_MAX to be LONG_MAX to optimize access_ok(),\nbecause the previous TASK_SIZE_MAX (default to TASK_SIZE) requires some\ncomputation.\n\nThe reasoning was that all user addresses are less than LONG_MAX, and all\nkernel addresses are greater than LONG_MAX. Therefore access_ok() can\nfilter kernel addresses.\n\nAddresses between TASK_SIZE and LONG_MAX are not valid user addresses, but\naccess_ok() let them pass. That was thought to be okay, because they are\nnot valid addresses at hardware level.\n\nUnfortunately, one case is missed: get_user_pages_fast() happily accepts\naddresses between TASK_SIZE and LONG_MAX. futex(), for instance, uses\nget_user_pages_fast(). This causes the problem reported by Robert [1].\n\nTherefore, revert this commit. TASK_SIZE_MAX is changed to the default:\nTASK_SIZE.\n\nThis unfortunately reduces performance, because TASK_SIZE is more expensive\nto compute compared to LONG_MAX. But correctness first, we can think about\noptimization later, if required."}], "id": "CVE-2025-38434", "lastModified": "2025-07-25T15:29:19.837", "metrics": {}, "published": "2025-07-25T15:15:28.707", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/890ba5be6335dbbbc99af14ea007befb5f83f174"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/f8b1898748dfeb4f9b67b6a6d661f354b9de3523"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/fe30c30bf3bb68d4a4d8c7c814769857b5c973e6"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Awaiting Analysis"}

{"bugzilla": {"description": "kernel: Revert \"riscv: Define TASK_SIZE_MAX for __access_ok()\"", "id": "2383456", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2383456"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "details": ["In the Linux kernel, the following vulnerability has been resolved:\nRevert \"riscv: Define TASK_SIZE_MAX for __access_ok()\"\nThis reverts commit ad5643cf2f69 (\"riscv: Define TASK_SIZE_MAX for\n__access_ok()\").\nThis commit changes TASK_SIZE_MAX to be LONG_MAX to optimize access_ok(),\nbecause the previous TASK_SIZE_MAX (default to TASK_SIZE) requires some\ncomputation.\nThe reasoning was that all user addresses are less than LONG_MAX, and all\nkernel addresses are greater than LONG_MAX. Therefore access_ok() can\nfilter kernel addresses.\nAddresses between TASK_SIZE and LONG_MAX are not valid user addresses, but\naccess_ok() let them pass. That was thought to be okay, because they are\nnot valid addresses at hardware level.\nUnfortunately, one case is missed: get_user_pages_fast() happily accepts\naddresses between TASK_SIZE and LONG_MAX. futex(), for instance, uses\nget_user_pages_fast(). This causes the problem reported by Robert [1].\nTherefore, revert this commit. TASK_SIZE_MAX is changed to the default:\nTASK_SIZE.\nThis unfortunately reduces performance, because TASK_SIZE is more expensive\nto compute compared to LONG_MAX. But correctness first, we can think about\noptimization later, if required."], "name": "CVE-2025-38434", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:10", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 10"}, {"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2025-07-25T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2025-38434\nhttps://nvd.nist.gov/vuln/detail/CVE-2025-38434\nhttps://lore.kernel.org/linux-cve-announce/2025072512-CVE-2025-38434-ecdf@gregkh/T"], "threat_severity": "Moderate"}