{"id":"AZL-96360","summary":"CVE-2026-74518 affecting package kernel 6.6.150.1-1","details":"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-\u003eregion_cache with freshly\nallocated file_region descriptors.  The allocation uses GFP_KERNEL, so\nresv-\u003elock is dropped around it: the new entries are gathered on a\nstack-local list head, allocated_regions, and spliced into\nresv-\u003eregion_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-\u003eregion_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-\u003eprev 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-\u003eregion_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.","modified":"2026-08-31T05:26:27Z","published":"2026-08-15T13:17:56Z","upstream":["CVE-2026-74518"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74518"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.150.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-96360.json"}}],"schema_version":"1.9.0"}