{"id":"AZL-110912","summary":"CVE-2026-99039 affecting package kernel 6.6.157.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nmemstick: core: wait for request completion before freeing card\n\nIn memstick_alloc_card() and memstick_set_rw_addr(),\nwait_for_completion_timeout() is used to wait for device identification\nand address configuration requests to complete.\n\nThe memstick subsystem does not provide an abort or cancellation\ncallback in struct memstick_host for in-flight requests. If\nwait_for_completion_timeout() expires (for instance, when a USB transfer\nor command retry is delayed), memstick_alloc_card() returns an error and\nfrees the memstick_dev structure via kfree(card).\n\nHowever, the host controller driver (such as rtsx_usb_ms) is still\nrunning the request asynchronously in worker context. When the transfer\neventually finishes, the driver writes into host-\u003ereq-\u003edata, which\npoints to memory inside the already freed card structure. This leads to\na KASAN slab-use-after-free write:\n\n  BUG: KASAN: slab-use-after-free in ms_read_bytes+0x8fe/0x990\n  Write of size 1 at addr ffff88813c188079 by task kworker/1:5/5239\n  Workqueue: events rtsx_usb_ms_handle_req\n  Call Trace:\n   ms_read_bytes+0x8fe/0x990 drivers/memstick/host/rtsx_usb_ms.c:450\n   rtsx_usb_ms_issue_cmd drivers/memstick/host/rtsx_usb_ms.c:477 [inline]\n   rtsx_usb_ms_handle_req+0x557/0x1a00 drivers/memstick/host/rtsx_usb_ms.c:531\n   process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396\n   worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560\n   kthread+0x373/0x450 kernel/kthread.c:436\n\n  Allocated by task 1662:\n   memstick_alloc_card drivers/memstick/core/memstick.c:383 [inline]\n   memstick_check+0x2c1/0x10d0 drivers/memstick/core/memstick.c:452\n   process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396\n\n  Freed by task 1662:\n   kfree+0x20c/0x650 mm/slub.c:6792\n   memstick_alloc_card drivers/memstick/core/memstick.c:420 [inline]\n   memstick_check+0x72b/0x10d0 drivers/memstick/core/memstick.c:452\n   process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396\n\nHost controller drivers (rtsx_usb_ms, jmb38x_ms, tifm_ms, r592) already\nimplement their own hardware and bus timeouts, and callers in\nmspro_block and ms_block already rely on wait_for_completion()\nunconditionally.\n\nReplace wait_for_completion_timeout() with wait_for_completion() in\nmemstick_set_rw_addr() and memstick_alloc_card() so that the card\nstructure is never freed while an asynchronous request is in flight.","modified":"2026-10-25T05:30:37Z","published":"2026-10-23T13:17:27Z","upstream":["CVE-2026-99039"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-99039"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"6.6.157.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-110912.json"}}],"schema_version":"1.9.0"}