GHSA-R8CV-6PG4-74WG
Vulnerability from github – Published: 2026-10-23 15:31 – Updated: 2026-10-23 15:31In the Linux kernel, the following vulnerability has been resolved:
memstick: core: wait for request completion before freeing card
In memstick_alloc_card() and memstick_set_rw_addr(), wait_for_completion_timeout() is used to wait for device identification and address configuration requests to complete.
The memstick subsystem does not provide an abort or cancellation callback in struct memstick_host for in-flight requests. If wait_for_completion_timeout() expires (for instance, when a USB transfer or command retry is delayed), memstick_alloc_card() returns an error and frees the memstick_dev structure via kfree(card).
However, the host controller driver (such as rtsx_usb_ms) is still running the request asynchronously in worker context. When the transfer eventually finishes, the driver writes into host->req->data, which points to memory inside the already freed card structure. This leads to a KASAN slab-use-after-free write:
BUG: KASAN: slab-use-after-free in ms_read_bytes+0x8fe/0x990 Write of size 1 at addr ffff88813c188079 by task kworker/1:5/5239 Workqueue: events rtsx_usb_ms_handle_req Call Trace: ms_read_bytes+0x8fe/0x990 drivers/memstick/host/rtsx_usb_ms.c:450 rtsx_usb_ms_issue_cmd drivers/memstick/host/rtsx_usb_ms.c:477 [inline] rtsx_usb_ms_handle_req+0x557/0x1a00 drivers/memstick/host/rtsx_usb_ms.c:531 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560 kthread+0x373/0x450 kernel/kthread.c:436
Allocated by task 1662: memstick_alloc_card drivers/memstick/core/memstick.c:383 [inline] memstick_check+0x2c1/0x10d0 drivers/memstick/core/memstick.c:452 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
Freed by task 1662: kfree+0x20c/0x650 mm/slub.c:6792 memstick_alloc_card drivers/memstick/core/memstick.c:420 [inline] memstick_check+0x72b/0x10d0 drivers/memstick/core/memstick.c:452 process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
Host controller drivers (rtsx_usb_ms, jmb38x_ms, tifm_ms, r592) already implement their own hardware and bus timeouts, and callers in mspro_block and ms_block already rely on wait_for_completion() unconditionally.
Replace wait_for_completion_timeout() with wait_for_completion() in memstick_set_rw_addr() and memstick_alloc_card() so that the card structure is never freed while an asynchronous request is in flight.
{
"affected": [],
"aliases": [
"CVE-2026-99039"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-23T13:17:27Z",
"severity": null
},
"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.",
"id": "GHSA-r8cv-6pg4-74wg",
"modified": "2026-10-23T15:31:36Z",
"published": "2026-10-23T15:31:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99039"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3af81770e2011c6ac7bb597a4af2e4f3591f928c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/810580cf60edc75c9891c2de3225e4cda78e4d9f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/aa0a37b5024d921e96ac4f8f487c8bfbf1f1a582"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c3ab92542475d59ae685cbb294e70ca4d0ba38e9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f2795c50144d528dabc2cf2fd53c0f0c63a823a1"
}
],
"schema_version": "1.4.0",
"severity": []
}
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