---
id: CVE-2026-98592
title: 'net: spacemit: clear TX descriptor on fragment mapping failure'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: spacemit: clear TX descriptor on fragment mapping failure

  emac_tx_mem_map() writes TX_DESC_0_OWN into the ring descriptor for
  every slot beyond old_head as soon a…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= bfec6d7f2001c7470c3cd261ae65a3ba8737f226 <
    ca9986cc824f2feb79b4a83e5f6f4c24c2140448
  - >-
    Linux >= bfec6d7f2001c7470c3cd261ae65a3ba8737f226 <
    3001a103a367c6051c43aff363b6979c10e65347
  - >-
    Linux >= bfec6d7f2001c7470c3cd261ae65a3ba8737f226 <
    2d14720beb58870b15a52b236c3ab0be0e06e915
  - Linux 6.18
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:19:04.373Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98592'
references:
  - url: 'https://git.kernel.org/stable/c/ca9986cc824f2feb79b4a83e5f6f4c24c2140448'
  - url: 'https://git.kernel.org/stable/c/3001a103a367c6051c43aff363b6979c10e65347'
  - url: 'https://git.kernel.org/stable/c/2d14720beb58870b15a52b236c3ab0be0e06e915'
tags:
  - cve.org
ingestedAt: '2026-10-18T15:45:12.249Z'
---

## Overview

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

net: spacemit: clear TX descriptor on fragment mapping failure

emac_tx_mem_map() writes TX_DESC_0_OWN into the ring descriptor for
every slot beyond old_head as soon as that slot's memset()'d local
copy is committed with "*tx_desc_addr = tx_desc", i.e. before the
buffers for that slot have necessarily all been mapped successfully.
If emac_tx_map_frag() then fails on a later fragment, the err_free_skb
path calls emac_free_tx_buf() to unmap and drop the skb, but leaves
the already-written descriptor memory untouched, and tx_ring->head is
never advanced past old_head (the "tx_ring->head = head" store is
skipped by the goto).

So a slot between old_head and the rolled-back head can be left with
TX_DESC_0_OWN set and buffer_addr_{1,2} pointing at DMA mappings that
emac_free_tx_buf() just tore down, while software considers that slot
free again. The next successful emac_tx_mem_map() call only rebuilds
old_head itself; if the DMA engine auto-advances into the following
descriptor once it finishes old_head's packet, it will fetch that
stale, already-unmapped address.

emac_tx_clean_desc() already treats emac_free_tx_buf() and clearing
the descriptor as a pair when reclaiming completed descriptors; do
the same in the mapping failure path.

## Affected

- `Linux >= bfec6d7f2001c7470c3cd261ae65a3ba8737f226 < ca9986cc824f2feb79b4a83e5f6f4c24c2140448`
- `Linux >= bfec6d7f2001c7470c3cd261ae65a3ba8737f226 < 3001a103a367c6051c43aff363b6979c10e65347`
- `Linux >= bfec6d7f2001c7470c3cd261ae65a3ba8737f226 < 2d14720beb58870b15a52b236c3ab0be0e06e915`
- `Linux 6.18`

## Remediation

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