---
id: CVE-2026-43250
title: 'usb: chipidea: udc: fix DMA and SG cleanup in _ep_nuke()'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  usb: chipidea: udc: fix DMA and SG cleanup in _ep_nuke()

  The ChipIdea UDC driver can encounter "not page aligned sg buffer"
  errors when a USB device is reconnected aft…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= aa69a8093ff985873cb44fe1157bd6db29a20fe4 <
    aad97c92119cb85db105ddda4a44c86cc0748e8c
  - >-
    Linux >= aa69a8093ff985873cb44fe1157bd6db29a20fe4 <
    1b72b834511d17f4d069d512f78671f3f210a2f1
  - >-
    Linux >= aa69a8093ff985873cb44fe1157bd6db29a20fe4 <
    f4fbf2d4750d12ac8525d2efac1016fa0d84d4ec
  - >-
    Linux >= aa69a8093ff985873cb44fe1157bd6db29a20fe4 <
    e74c436f8568af1c60942469d0a2300b3ada3857
  - >-
    Linux >= aa69a8093ff985873cb44fe1157bd6db29a20fe4 <
    cea2a1257a3b5ea3e769a445b34af13e6aa5a123
  - Linux 2.6.29
published: '2026-05-06'
updated: '2026-10-21'
sourceUpdated: '2026-10-21T12:40:25.395Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-43250'
references:
  - url: 'https://git.kernel.org/stable/c/aad97c92119cb85db105ddda4a44c86cc0748e8c'
  - url: 'https://git.kernel.org/stable/c/1b72b834511d17f4d069d512f78671f3f210a2f1'
  - url: 'https://git.kernel.org/stable/c/f4fbf2d4750d12ac8525d2efac1016fa0d84d4ec'
  - url: 'https://git.kernel.org/stable/c/e74c436f8568af1c60942469d0a2300b3ada3857'
  - url: 'https://git.kernel.org/stable/c/cea2a1257a3b5ea3e769a445b34af13e6aa5a123'
tags:
  - cve.org
epss: 0.00175
epssPercentile: 0.06623
ingestedAt: '2026-10-21T12:48:53.643Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

usb: chipidea: udc: fix DMA and SG cleanup in _ep_nuke()

The ChipIdea UDC driver can encounter "not page aligned sg buffer"
errors when a USB device is reconnected after being disconnected
during an active transfer. This occurs because _ep_nuke() returns
requests to the gadget layer without properly unmapping DMA buffers
or cleaning up scatter-gather bounce buffers.

Root cause:
When a disconnect happens during a multi-segment DMA transfer, the
request's num_mapped_sgs field and sgt.sgl pointer remain set with
stale values. The request is returned to the gadget driver with status
-ESHUTDOWN but still has active DMA state. If the gadget driver reuses
this request on reconnect without reinitializing it, the stale DMA
state causes _hardware_enqueue() to skip DMA mapping (seeing non-zero
num_mapped_sgs) and attempt to use freed/invalid DMA addresses,
leading to alignment errors and potential memory corruption.

The normal completion path via _hardware_dequeue() properly calls
usb_gadget_unmap_request_by_dev() and sglist_do_debounce() before
returning the request. The _ep_nuke() path must do the same cleanup
to ensure requests are returned in a clean, reusable state.

Fix:
Add DMA unmapping and bounce buffer cleanup to _ep_nuke() to mirror
the cleanup sequence in _hardware_dequeue():
- Call usb_gadget_unmap_request_by_dev() if num_mapped_sgs is set
- Call sglist_do_debounce() with copy=false if bounce buffer exists

This ensures that when requests are returned due to endpoint shutdown,
they don't retain stale DMA mappings. The 'false' parameter to
sglist_do_debounce() prevents copying data back (appropriate for
shutdown path where transfer was aborted).

## Affected

- `Linux >= aa69a8093ff985873cb44fe1157bd6db29a20fe4 < aad97c92119cb85db105ddda4a44c86cc0748e8c`
- `Linux >= aa69a8093ff985873cb44fe1157bd6db29a20fe4 < 1b72b834511d17f4d069d512f78671f3f210a2f1`
- `Linux >= aa69a8093ff985873cb44fe1157bd6db29a20fe4 < f4fbf2d4750d12ac8525d2efac1016fa0d84d4ec`
- `Linux >= aa69a8093ff985873cb44fe1157bd6db29a20fe4 < e74c436f8568af1c60942469d0a2300b3ada3857`
- `Linux >= aa69a8093ff985873cb44fe1157bd6db29a20fe4 < cea2a1257a3b5ea3e769a445b34af13e6aa5a123`
- `Linux 2.6.29`

## Remediation

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