{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-40245", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-04-16T07:20:57.181Z", "datePublished": "2025-12-04T15:31:34.142Z", "dateUpdated": "2026-08-05T12:08:49.485Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:08:49.485Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnios2: ensure that memblock.current_limit is set when setting pfn limits\n\nOn nios2, with CONFIG_FLATMEM set, the kernel relies on\nmemblock_get_current_limit() to determine the limits of mem_map, in\nparticular for max_low_pfn.\nUnfortunately, memblock.current_limit is only default initialized to\nMEMBLOCK_ALLOC_ANYWHERE at this point of the bootup, potentially leading\nto situations where max_low_pfn can erroneously exceed the value of\nmax_pfn and, thus, the valid range of available DRAM.\n\nThis can in turn cause kernel-level paging failures, e.g.:\n\n[ 76.900000] Unable to handle kernel paging request at virtual address 20303000\n[ 76.900000] ea = c0080890, ra = c000462c, cause = 14\n[ 76.900000] Kernel panic - not syncing: Oops\n[ 76.900000] ---[ end Kernel panic - not syncing: Oops ]---\n\nThis patch fixes this by pre-calculating memblock.current_limit\nbased on the upper limits of the available memory ranges via\nadjust_lowmem_bounds, a simplified version of the equivalent\nimplementation within the arm architecture." } ], "metrics": [ { "cvssV3_1": { "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" }, "scenarios": [ { "lang": "en", "value": "AV:L - The defect is in nios2 `setup_arch()` boot-time memory initialization, and its consequences are realized through local activity — memory allocation and `mmap()`/page-fault paths that call `pfn_valid()`/`pfn_to_page()`. There is no network or remote-peer path to arch/nios2/kernel/setup.c.\nAC:L - `memblock.current_limit` is never set before `find_limits()`, so `max_low_pfn`/`max_mapnr` are unconditionally inflated to ~4 GB of PFNs on every affected nios2 system — the vulnerable state always exists, with no race and no memory-layout luck required. The attacker only needs to map or touch a physical region above DRAM, which is under their control on these FPGA SoCs where peripheral/on-chip-memory windows sit above RAM.\nPR:L - No capability check guards any of it — an ordinary unprivileged process reaching `update_mmu_cache_range()`/`flush_dcache_page()` through a fault on a device or PFNMAP mapping, or simply driving allocation into the bogus PFN range, is sufficient. Embedded nios2 deployments routinely expose UIO/framebuffer device nodes to non-root users.\nUI:N - The attacker performs every step themselves — map the region, touch it, let the fault path run. No action by another user or administrator is needed.\nS:U - The out-of-bounds accesses stay within the kernel's own memory and security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - `pfn_valid()` wrongly approves PFNs with no memmap entry, so `pfn_to_page()` returns a pointer up to tens of megabytes past the end of `mem_map`, and `folio_flush_mapping()`/`flush_aliases()` read and follow that out-of-bounds kernel data as an `address_space`. This is a wide, PFN-indexed out-of-bounds read, far beyond a strictly bounded few bytes.\nI:H - `update_mmu_cache_range()` performs `test_and_set_bit(PG_dcache_clean, &folio->flags.f)` on the out-of-bounds `struct page`, an attacker-positioned out-of-bounds atomic write into arbitrary kernel memory, and then walks a garbage `address_space`/i_mmap tree. Per the OOB-write guidance this is High.\nA:H - The documented, reproduced impact is a fatal kernel paging fault and panic (\"Unable to handle kernel paging request ... Kernel panic - not syncing: Oops\"), and the corrupted low-memory limits can equally cause the allocator and DMA logic to operate on non-existent DRAM. The condition is triggerable repeatedly at will." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/nios2/kernel/setup.c" ], "versions": [ { "version": "7f7bc20bc41a4fbcd2db75b375ac95e5faf958ae", "lessThan": "25f09699edd360b534ccae16bc276c3b52c471f3", "status": "affected", "versionType": "git" }, { "version": "7f7bc20bc41a4fbcd2db75b375ac95e5faf958ae", "lessThan": "5c3e38a367822f036227dd52bac82dc4a05157e2", "status": "affected", "versionType": "git" }, { "version": "7f7bc20bc41a4fbcd2db75b375ac95e5faf958ae", "lessThan": "b1ec9faef7e36269ca3ec890972a78effbaeb975", "status": "affected", "versionType": "git" }, { "version": "7f7bc20bc41a4fbcd2db75b375ac95e5faf958ae", "lessThan": "90f5f715550e07cd6a51f80fc3f062d832c8c997", "status": "affected", "versionType": "git" }, { "version": "7f7bc20bc41a4fbcd2db75b375ac95e5faf958ae", "lessThan": "8912814f14e298b83df072fecc1f7ed1b63b1b2c", "status": "affected", "versionType": "git" }, { "version": "7f7bc20bc41a4fbcd2db75b375ac95e5faf958ae", "lessThan": "a20b83cf45be2057f3d073506779e52c7fa17f94", "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/nios2/kernel/setup.c" ], "versions": [ { "version": "5.12", "status": "affected" }, { "version": "0", "lessThan": "5.12", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.196", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.158", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.115", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.56", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.17.6", "lessThanOrEqual": "6.17.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18", "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": "5.12", "versionEndExcluding": "5.15.196" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.1.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.6.115" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.12.56" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.17.6" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.12", "versionEndExcluding": "6.18" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/25f09699edd360b534ccae16bc276c3b52c471f3" }, { "url": "https://git.kernel.org/stable/c/5c3e38a367822f036227dd52bac82dc4a05157e2" }, { "url": "https://git.kernel.org/stable/c/b1ec9faef7e36269ca3ec890972a78effbaeb975" }, { "url": "https://git.kernel.org/stable/c/90f5f715550e07cd6a51f80fc3f062d832c8c997" }, { "url": "https://git.kernel.org/stable/c/8912814f14e298b83df072fecc1f7ed1b63b1b2c" }, { "url": "https://git.kernel.org/stable/c/a20b83cf45be2057f3d073506779e52c7fa17f94" } ], "title": "nios2: ensure that memblock.current_limit is set when setting pfn limits", "x_generator": { "engine": "bippy-1.2.0" } } } }