---
id: CVE-2026-93228
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  svcrdma: Reject Write/Reply chunks with segcount 0

  A peer can send a Write or Reply chunk whose segcount field is zero.
  xdr_check_write_chunk() only rejects segcount >…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  svcrdma: Reject Write/Reply chunks with segcount 0

  A peer can send a Write or Reply chunk whose segcount field is zero.
  xdr_check_write_chunk() only rejects segcount >…
severity: critical
cvss: 9.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 <
    fe533ae1bed2ef2b3d54ee7ab410da1874ed3d4f
  - >-
    Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 <
    a798714b58041e88716db3bf8fb03ae13eecd54a
  - >-
    Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 <
    45dbdb2637b7fc5f1355b588780d2a7fb0516805
  - >-
    Linux >= 78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 <
    9808eb7656666acc7291bae9ab6b987bd16e47e0
  - Linux 5.11
published: '2026-09-24'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T05:17:00.567'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-93228'
references:
  - url: 'https://git.kernel.org/stable/c/45dbdb2637b7fc5f1355b588780d2a7fb0516805'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9808eb7656666acc7291bae9ab6b987bd16e47e0'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/a798714b58041e88716db3bf8fb03ae13eecd54a'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/fe533ae1bed2ef2b3d54ee7ab410da1874ed3d4f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-24T15:45:56.662Z'
---

## Overview

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

svcrdma: Reject Write/Reply chunks with segcount 0

A peer can send a Write or Reply chunk whose segcount field is zero.
xdr_check_write_chunk() only rejects segcount > rc_maxpages, so zero
passes the range check, and xdr_inline_decode(stream, 0) returns the
current (non-NULL) cursor without advancing. The function returns
true and pcl_alloc_write() then links a struct svc_rdma_chunk with
ch_segcount == 0 onto rc_write_pcl or rc_reply_pcl.

An earlier patch in this series made pcl_for_each_segment() safe for
ch_segcount == 0, so this no longer drives the memory walk it used
to. Rejecting the malformed frame at the decode boundary is still
worthwhile as defense in depth: it keeps degenerate zero-segment
chunks off the parsed chunk lists entirely, so any future consumer
that walks ch_segments directly cannot observe one, and it makes the
zero-floor easy to backport to trees where the macro change is more
intrusive. RFC 8166 has no meaning for a Write/Reply chunk that
describes no remote buffer, so no legitimate client is affected.

xdr_check_reply_chunk() funnels Reply chunks through
xdr_check_write_chunk() and inherits the same rejection.

pcl_alloc_write() also links each chunk onto the parsed chunk list
before filling its segment array. If a future change weakens the
segcount-0 rejection, an incomplete chunk is visible to consumers
during the fill loop. Reorder so that list_add_tail() follows the
segment fill loop, ensuring only fully-populated chunks appear on
the list.

## Remediation

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