{"id":"AZL-83861","summary":"CVE-2026-31578 affecting package kernel for versions less than 6.6.137.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmedia: as102: fix to not free memory after the device is registered in as102_usb_probe()\n\nIn as102_usb driver, the following race condition occurs:\n```\n\t\tCPU0\t\t\t\t\t\tCPU1\nas102_usb_probe()\n  kzalloc(); // alloc as102_dev_t\n  ....\n  usb_register_dev();\n\t\t\t\t\t\tfd = sys_open(\"/path/to/dev\"); // open as102 fd\n\t\t\t\t\t\t....\n  usb_deregister_dev();\n  ....\n  kfree(); // free as102_dev_t\n  ....\n\t\t\t\t\t\tsys_close(fd);\n\t\t\t\t\t\t  as102_release() // UAF!!\n\t\t\t\t\t\t    as102_usb_release()\n\t\t\t\t\t\t      kfree(); // DFB!!\n```\n\nWhen a USB character device registered with usb_register_dev() is later\nunregistered (via usb_deregister_dev() or disconnect), the device node is\nremoved so new open() calls fail. However, file descriptors that are\nalready open do not go away immediately: they remain valid until the last\nreference is dropped and the driver's .release() is invoked.\n\nIn as102, as102_usb_probe() calls usb_register_dev() and then, on an\nerror path, does usb_deregister_dev() and frees as102_dev_t right away.\nIf userspace raced a successful open() before the deregistration, that\nopen FD will later hit as102_release() --\u003e as102_usb_release() and access\nor free as102_dev_t again, occur a race to use-after-free and\ndouble-free vuln.\n\nThe fix is to never kfree(as102_dev_t) directly once usb_register_dev()\nhas succeeded. After deregistration, defer freeing memory to .release().\n\nIn other words, let release() perform the last kfree when the final open\nFD is closed.","modified":"2026-08-28T17:48:03.444706794Z","published":"2026-04-24T15:16:32Z","upstream":["CVE-2026-31578"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-31578"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.137.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-83861.json"}}],"schema_version":"1.9.0"}