{"cve":"CVE-2026-74518","nvd":{"published":"2026-08-15T13:17:56.967","modified":"2026-10-16T20:17:34.450","status":"Received","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nmm/hugetlb: fix list corruption in allocate_file_region_entries()\n\nallocate_file_region_entries() tops up resv->region_cache with freshly\nallocated file_region descriptors.  The allocation uses GFP_KERNEL, so\nresv->lock is dropped around it: the new entries are gathered on a\nstack-local list head, allocated_regions, and spliced into\nresv->region_cache once the lock is re-acquired.\n\nThe splice used list_splice(), which moves the entries but does not\nre-initialize the source head, so allocated_regions is left pointing at an\nentry that now lives on resv->region_cache.  The top-up runs in a while\nloop that re-checks the cache deficit after re-acquiring the lock.  For a\nshared mapping the resv_map is shared by every mapper of the hugetlbfs\ninode, so a concurrent region_chg()/region_add()/region_del() on the same\nresv_map can consume cache entries during the unlocked window and force a\nsecond iteration.  That iteration calls list_add() on the stale head and\ncorrupts the list; with CONFIG_DEBUG_LIST the __list_add_valid() check\ntrips:\n\n  list_add corruption. next->prev should be prev (ffffc900011ff7f8),\n  but was ffff88814c281460. (next=ffff88814c545640).\n  kernel BUG at lib/list_debug.c:31!\n   allocate_file_region_entries+0x191/0x420\n   region_chg+0x267/0x300\n   hugetlb_reserve_pages+0x387/0xc80\n   hugetlbfs_file_mmap+0x2ce/0x3f0\n   mmap_region+0x1348/0x1a80\n   do_mmap+0x85e/0xb90\n   vm_mmap_pgoff+0x18c/0x330\n   ksys_mmap_pgoff+0x2a1/0x3e0\n   do_syscall_64+0xd7/0x420\n\nWithout CONFIG_DEBUG_LIST the bad list_add() silently links a kernel-stack\naddress into resv->region_cache, leading to later use-after-free.\n\nThis was observed as a real host panic on a dense KVM host where a QEMU\nguest-RAM hugetlbfs file was mapped MAP_SHARED by both QEMU and a separate\nSPDK/DPDK vhost-user target, generating concurrent region_* traffic on one\nshared resv_map.\n\nUse list_splice_init() so the source head is re-initialized empty after\neach splice, making the retry loop safe.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":[],"references":["https://git.kernel.org/stable/c/01b8569233e47693d6ff7efa96d9854c55f936fc","https://git.kernel.org/stable/c/126a70bf1a08ddc9d79c471ebdaa2b08cfbab8df","https://git.kernel.org/stable/c/587a0accc2b4fccc5cf7baf0fe34e50efde51f9c","https://git.kernel.org/stable/c/62e1c2741a4d923d9854efd5927a6212aad7a187","https://git.kernel.org/stable/c/9c5fdffc5e1ce84403c58289ee72697051803bf7"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:49:10.689564601+00:00"},"epss":{"cve":"CVE-2026-74518","score":0.00126,"percentile":0.02235,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}