---
id: CVE-2026-98900
title: 'xen/gntalloc: validate grant count before allocation'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  xen/gntalloc: validate grant count before allocation

  gntalloc_ioctl_alloc() allocates the grant-id array before checking
  whether the requested count fits within the gl…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    71a0cf87e19fb35c4292ca88985e376e613c900a
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    641de086a05f349de7fc548612432bc2fed721ca
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    720554c04acba80018ded069d3e0984bebaee891
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    84d5727cef8eb9c8a28210ad248f1c70b223b065
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    231542f4e43cf9837cb520664545e85fbe666b7b
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    2299822f3f466b5dcad2377bf63986199f881a6b
  - Linux < 5.10.271
  - Linux < 5.15.222
  - Linux < 6.1.189
  - Linux < 6.6.158
  - Linux < 6.12.111
  - Linux < 6.18.53
  - Linux (all versions)
published: '2026-10-23'
updated: '2026-10-23'
sourceUpdated: '2026-10-23T11:54:10.566Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98900'
references:
  - url: 'https://git.kernel.org/stable/c/e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8'
  - url: 'https://git.kernel.org/stable/c/71a0cf87e19fb35c4292ca88985e376e613c900a'
  - url: 'https://git.kernel.org/stable/c/641de086a05f349de7fc548612432bc2fed721ca'
  - url: 'https://git.kernel.org/stable/c/720554c04acba80018ded069d3e0984bebaee891'
  - url: 'https://git.kernel.org/stable/c/84d5727cef8eb9c8a28210ad248f1c70b223b065'
  - url: 'https://git.kernel.org/stable/c/231542f4e43cf9837cb520664545e85fbe666b7b'
  - url: 'https://git.kernel.org/stable/c/2299822f3f466b5dcad2377bf63986199f881a6b'
tags:
  - cve.org
ingestedAt: '2026-10-23T13:24:55.574Z'
---

## Overview

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

xen/gntalloc: validate grant count before allocation

gntalloc_ioctl_alloc() allocates the grant-id array before checking
whether the requested count fits within the global grant limit. Counts
above that limit cannot succeed, so reject them before the
user-controlled allocation reaches kcalloc().

Use a subtraction-based check while holding gref_mutex so adding the
requested count cannot wrap. Also cast the count before advancing the
per-file index so the page-size multiplication is performed in 64-bit
arithmetic.

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < e2806390aa1c4d5b3f7a68f10a56ae12c71c00d8`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 71a0cf87e19fb35c4292ca88985e376e613c900a`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 641de086a05f349de7fc548612432bc2fed721ca`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 720554c04acba80018ded069d3e0984bebaee891`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 84d5727cef8eb9c8a28210ad248f1c70b223b065`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 231542f4e43cf9837cb520664545e85fbe666b7b`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 2299822f3f466b5dcad2377bf63986199f881a6b`
- `Linux < 5.10.271`
- `Linux < 5.15.222`
- `Linux < 6.1.189`
- `Linux < 6.6.158`
- `Linux < 6.12.111`
- `Linux < 6.18.53`
- `Linux (all versions)`

## Remediation

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