{"id":"AZL-92855","summary":"CVE-2026-64192 affecting package kernel for versions less than 6.6.150.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject BPF_MAP_TYPE_INODE_STORAGE creation if BPF LSM is uninitialized\n\nWhen CONFIG_BPF_LSM=y is set, BPF inode storage maps\n(BPF_MAP_TYPE_INODE_STORAGE) are compiled into the kernel. However,\nif the BPF LSM is not explicitly enabled at boot time (e.g. omitted\nfrom the \"lsm=\" boot parameter), lsm_prepare() is never executed for\nthe BPF LSM.\n\nConsequently, the BPF inode security blob offset\n(bpf_lsm_blob_sizes.lbs_inode) is never initialized and remains at\nits default compiled size of 8 bytes instead of being updated to a\nvalid offset past the reserved struct rcu_head (typically 16 bytes\nor more).\n\nWhen a privileged user creates and updates a BPF_MAP_TYPE_INODE_STORAGE\nmap, bpf_inode() evaluates inode-\u003ei_security + 8. This erroneously\naliases the struct rcu_head.func callback pointer at the beginning\nof the inode-\u003ei_security blob. During subsequent map element cleanup\nor inode destruction, writing NULL to owner_storage clears the queued\nRCU callback pointer. When rcu_do_batch() later executes the queued\ncallback, it attempts an instruction fetch at address 0x0, triggering\nan immediate kernel panic.\n\nFix this by introducing a global bpf_lsm_initialized boolean flag\nmarked with __ro_after_init. Set this flag to true inside bpf_lsm_init()\nwhen the LSM framework successfully registers the BPF LSM. Gate map\nallocation in inode_storage_map_alloc() on this flag, returning\n-EOPNOTSUPP if the BPF LSM is in turn uninitialized.\n\nThis fail-fast approach prevents userspace from allocating inode\nstorage maps when the supporting BPF LSM infrastructure is absent,\navoiding zombie map states.","modified":"2026-08-28T17:47:39.407527237Z","published":"2026-07-20T17:18:22Z","upstream":["CVE-2026-64192"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64192"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.150.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-92855.json"}}],"schema_version":"1.9.0"}