{"id":"CVE-2024-42235","state":"PUBLISHED","title":"s390/mm: Add NULL pointer check to crst_table_free() base_crst_free()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ns390/mm: Add NULL pointer check to crst_table_free() base_crst_free()\n\ncrst_table_free() used to work with NULL pointers before the conversion\nto ptdescs.  Since crst_table_free() can be called with a NULL pointer\n(error handling in crst_table_upgrade() add an explicit check.\n\nAlso add the same check to base_crst_free() for consistency reasons.\n\nIn real life this should not happen, since order two GFP_KERNEL\nallocations will not fail, unless FAIL_PAGE_ALLOC is enabled and used.","publishedAt":"2024-08-07T15:14:25.070Z","updatedAt":"2026-08-05T11:36:00.433Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"6326c26c1514757242829b292b26eac589013200","status":"affected","lessThan":"794fa52b94637d6b2e8c9474fbe3983af5c9f046","versionType":"git"},{"version":"6326c26c1514757242829b292b26eac589013200","status":"affected","lessThan":"f80bd8bb6f380bc265834c46058d38b34174813e","versionType":"git"},{"version":"6326c26c1514757242829b292b26eac589013200","status":"affected","lessThan":"b5efb63acf7bddaf20eacfcac654c25c446eabe8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/s390/mm/pgalloc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.6","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.6","versionType":"semver"},{"version":"6.6.41","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.9.10","status":"unaffected","lessThanOrEqual":"6.9.*","versionType":"semver"},{"version":"6.10","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/s390/mm/pgalloc.c"]}],"references":["https://git.kernel.org/stable/c/794fa52b94637d6b2e8c9474fbe3983af5c9f046","https://git.kernel.org/stable/c/f80bd8bb6f380bc265834c46058d38b34174813e","https://git.kernel.org/stable/c/b5efb63acf7bddaf20eacfcac654c25c446eabe8"],"weaknesses":[],"ingestedAt":"2026-10-29T20:07:47.831Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2024/42xxx/CVE-2024-42235.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2024-42235","state":"PUBLISHED","datePublished":"2024-08-07T15:14:25.070Z","dateUpdated":"2026-08-05T11:36:00.433Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-07-30T07:40:12.252Z"},"containers":{"cna":{"title":"s390/mm: Add NULL pointer check to crst_table_free() base_crst_free()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ns390/mm: Add NULL pointer check to crst_table_free() base_crst_free()\n\ncrst_table_free() used to work with NULL pointers before the conversion\nto ptdescs.  Since crst_table_free() can be called with a NULL pointer\n(error handling in crst_table_upgrade() add an explicit check.\n\nAlso add the same check to base_crst_free() for consistency reasons.\n\nIn real life this should not happen, since order two GFP_KERNEL\nallocations will not fail, unless FAIL_PAGE_ALLOC is enabled and used."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"6326c26c1514757242829b292b26eac589013200","status":"affected","lessThan":"794fa52b94637d6b2e8c9474fbe3983af5c9f046","versionType":"git"},{"version":"6326c26c1514757242829b292b26eac589013200","status":"affected","lessThan":"f80bd8bb6f380bc265834c46058d38b34174813e","versionType":"git"},{"version":"6326c26c1514757242829b292b26eac589013200","status":"affected","lessThan":"b5efb63acf7bddaf20eacfcac654c25c446eabe8","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/s390/mm/pgalloc.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.6","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.6","versionType":"semver"},{"version":"6.6.41","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.9.10","status":"unaffected","lessThanOrEqual":"6.9.*","versionType":"semver"},{"version":"6.10","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["arch/s390/mm/pgalloc.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/794fa52b94637d6b2e8c9474fbe3983af5c9f046"},{"url":"https://git.kernel.org/stable/c/f80bd8bb6f380bc265834c46058d38b34174813e"},{"url":"https://git.kernel.org/stable/c/b5efb63acf7bddaf20eacfcac654c25c446eabe8"}],"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 vulnerable path is entered only through a local `mmap()`/`mremap()`/`shmat()` syscall on s390, via `arch_get_unmapped_area()` → `check_asce_limit()` → `crst_table_upgrade()`. No network, adjacent-network, or remote-peer data reaches this code.\nAC:L - The attacker fully controls the address-space geometry needed (two ordinary high-address mmaps drive `asce_limit` to `_REGION1_SIZE` and then request a 5-level upgrade, leaving `p4d == NULL`), and can engineer the required order-2 `GFP_KERNEL` failure by driving their own multithreaded process into the OOM-victim state that makes `__alloc_pages_slowpath()` return NULL, retrying as often as needed. Every attempt is cheap and repeatable, so the remaining timing window is one the attacker creates rather than one beyond their control.\nPR:L - Any unprivileged local user can call `mmap()` with a high address hint — there is no capability check, namespace requirement, or privileged device node anywhere between the syscall entry and `crst_table_free()`. On IBM Z / LinuxONE hosts this means any shared-tenant, container, or shell user.\nUI:N - The whole sequence is performed by the attacking process itself through ordinary syscalls; no victim must mount a filesystem, open a device, or take any other action.\nS:U - The corrupted page-allocator state and the freed reserved page remain entirely within the kernel's own security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - On 6.6.y the reserved PFN 0 (the s390 absolute-zero lowcore holding restart PSWs and `restart_fn`/`restart_data` kernel pointers plus machine-check save areas) is released into the buddy allocator with the sanity checks compiled out, so it can be handed to an attacker-influenced allocation still containing that firmware/kernel state; repeating the trigger underflows the refcount of whatever page then occupies PFN 0, yielding a use-after-free read primitive over live kernel memory.\nI:H - Injecting a memblock-reserved page into the buddy free lists breaks the allocator's ownership invariant — the page is concurrently written by hardware/firmware (store status, machine-check save area) while owned by another kernel object or user mapping — and the refcount underflow on repeat triggers gives a double-free/page-reuse primitive, the classic route to controlled kernel writes.\nA:H - On 6.9/6.10 the underflowed `__pa(0)` produces a wild `struct page *` that faults in `compound_order()`, oopsing the kernel; on 6.6.y with page-checking enabled it produces a \"BUG: Bad page state\" splat and `TAINT_BAD_PAGE` (a panic under `panic_on_taint`), and with checks off the corrupted allocator state leads to subsequent oops/panic."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T11:36:00.433Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.6.41"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.9.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.10"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2024-42235","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2024-09-10T16:14:07.518719Z"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2024-09-11T17:34:32.266Z"}}]}}}