---
id: CVE-2026-99039
title: 'memstick: core: wait for request completion before freeing card'
summary: |-
  In 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 …
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= baf8532a147d5b76681ce040e2c8f25a3f0e718d <
    c3ab92542475d59ae685cbb294e70ca4d0ba38e9
  - >-
    Linux >= baf8532a147d5b76681ce040e2c8f25a3f0e718d <
    810580cf60edc75c9891c2de3225e4cda78e4d9f
  - >-
    Linux >= baf8532a147d5b76681ce040e2c8f25a3f0e718d <
    f2795c50144d528dabc2cf2fd53c0f0c63a823a1
  - >-
    Linux >= baf8532a147d5b76681ce040e2c8f25a3f0e718d <
    3af81770e2011c6ac7bb597a4af2e4f3591f928c
  - >-
    Linux >= baf8532a147d5b76681ce040e2c8f25a3f0e718d <
    aa0a37b5024d921e96ac4f8f487c8bfbf1f1a582
  - Linux 2.6.25
published: '2026-10-23'
updated: '2026-10-23'
sourceUpdated: '2026-10-23T12:21:57.421Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-99039'
references:
  - url: 'https://git.kernel.org/stable/c/c3ab92542475d59ae685cbb294e70ca4d0ba38e9'
  - url: 'https://git.kernel.org/stable/c/810580cf60edc75c9891c2de3225e4cda78e4d9f'
  - url: 'https://git.kernel.org/stable/c/f2795c50144d528dabc2cf2fd53c0f0c63a823a1'
  - url: 'https://git.kernel.org/stable/c/3af81770e2011c6ac7bb597a4af2e4f3591f928c'
  - url: 'https://git.kernel.org/stable/c/aa0a37b5024d921e96ac4f8f487c8bfbf1f1a582'
tags:
  - cve.org
ingestedAt: '2026-10-23T13:24:55.528Z'
---

## Overview

In 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

- `Linux >= baf8532a147d5b76681ce040e2c8f25a3f0e718d < c3ab92542475d59ae685cbb294e70ca4d0ba38e9`
- `Linux >= baf8532a147d5b76681ce040e2c8f25a3f0e718d < 810580cf60edc75c9891c2de3225e4cda78e4d9f`
- `Linux >= baf8532a147d5b76681ce040e2c8f25a3f0e718d < f2795c50144d528dabc2cf2fd53c0f0c63a823a1`
- `Linux >= baf8532a147d5b76681ce040e2c8f25a3f0e718d < 3af81770e2011c6ac7bb597a4af2e4f3591f928c`
- `Linux >= baf8532a147d5b76681ce040e2c8f25a3f0e718d < aa0a37b5024d921e96ac4f8f487c8bfbf1f1a582`
- `Linux 2.6.25`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.