{"id":"AZL-66401","summary":"CVE-2025-38527 affecting package kernel for versions less than 6.6.104.2-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix use-after-free in cifs_oplock_break\n\nA race condition can occur in cifs_oplock_break() leading to a\nuse-after-free of the cinode structure when unmounting:\n\n  cifs_oplock_break()\n    _cifsFileInfo_put(cfile)\n      cifsFileInfo_put_final()\n        cifs_sb_deactive()\n          [last ref, start releasing sb]\n            kill_sb()\n              kill_anon_super()\n                generic_shutdown_super()\n                  evict_inodes()\n                    dispose_list()\n                      evict()\n                        destroy_inode()\n                          call_rcu(&inode-\u003ei_rcu, i_callback)\n    spin_lock(&cinode-\u003eopen_file_lock)  \u003c- OK\n                            [later] i_callback()\n                              cifs_free_inode()\n                                kmem_cache_free(cinode)\n    spin_unlock(&cinode-\u003eopen_file_lock)  \u003c- UAF\n    cifs_done_oplock_break(cinode)       \u003c- UAF\n\nThe issue occurs when umount has already released its reference to the\nsuperblock. When _cifsFileInfo_put() calls cifs_sb_deactive(), this\nreleases the last reference, triggering the immediate cleanup of all\ninodes under RCU. However, cifs_oplock_break() continues to access the\ncinode after this point, resulting in use-after-free.\n\nFix this by holding an extra reference to the superblock during the\nentire oplock break operation. This ensures that the superblock and\nits inodes remain valid until the oplock break completes.","modified":"2026-04-01T05:20:57.592337Z","published":"2025-08-16T12:15:28Z","upstream":["CVE-2025-38527"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-38527"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.104.2-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-66401.json"}}],"schema_version":"1.7.5"}