{"id":"CVE-2026-74518","title":"mm/hugetlb: fix list corruption in allocate_file_region_entries()","summary":"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 descript…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 01b8569233e47693d6ff7efa96d9854c55f936fc","Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 9c5fdffc5e1ce84403c58289ee72697051803bf7","Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < f3e54f6a5e1681f83d13e8716bc92ef5ecf121d3","Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 62e1c2741a4d923d9854efd5927a6212aad7a187","Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 587a0accc2b4fccc5cf7baf0fe34e50efde51f9c","Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 126a70bf1a08ddc9d79c471ebdaa2b08cfbab8df","Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < ac1bb7fd45088d0db57a22ce7729f258ebd63cf5","Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < dd9623f58ec702a07b2d67179d6fcea79c52231a","Linux 5.10"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T18:58:55.418677Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T19:05:52.396Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74518","references":[{"url":"https://git.kernel.org/stable/c/01b8569233e47693d6ff7efa96d9854c55f936fc"},{"url":"https://git.kernel.org/stable/c/9c5fdffc5e1ce84403c58289ee72697051803bf7"},{"url":"https://git.kernel.org/stable/c/f3e54f6a5e1681f83d13e8716bc92ef5ecf121d3"},{"url":"https://git.kernel.org/stable/c/62e1c2741a4d923d9854efd5927a6212aad7a187"},{"url":"https://git.kernel.org/stable/c/587a0accc2b4fccc5cf7baf0fe34e50efde51f9c"},{"url":"https://git.kernel.org/stable/c/126a70bf1a08ddc9d79c471ebdaa2b08cfbab8df"},{"url":"https://git.kernel.org/stable/c/ac1bb7fd45088d0db57a22ce7729f258ebd63cf5"},{"url":"https://git.kernel.org/stable/c/dd9623f58ec702a07b2d67179d6fcea79c52231a"}],"tags":["cve.org"],"epss":0.00126,"epssPercentile":0.02029,"ingestedAt":"2026-10-16T19:46:24.349Z","slug":"CVE-2026-74518","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 01b8569233e47693d6ff7efa96d9854c55f936fc`\n- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 9c5fdffc5e1ce84403c58289ee72697051803bf7`\n- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < f3e54f6a5e1681f83d13e8716bc92ef5ecf121d3`\n- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 62e1c2741a4d923d9854efd5927a6212aad7a187`\n- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 587a0accc2b4fccc5cf7baf0fe34e50efde51f9c`\n- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < 126a70bf1a08ddc9d79c471ebdaa2b08cfbab8df`\n- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < ac1bb7fd45088d0db57a22ce7729f258ebd63cf5`\n- `Linux >= d3ec7b6e09e512ba902b86bcca2c512fb06d492f < dd9623f58ec702a07b2d67179d6fcea79c52231a`\n- `Linux 5.10`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}