---
id: CVE-2026-80864
title: 'RDMA/rxe: Fix responder UAF on IB_QP_MAX_DEST_RD_ATOMIC modify_qp'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  RDMA/rxe: Fix responder UAF on IB_QP_MAX_DEST_RD_ATOMIC modify_qp

  rxe_qp_from_attr() handles IB_QP_MAX_DEST_RD_ATOMIC outside the
  IB_QP_STATE path, so it holds no stat…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 <
    0136b528b753c5a56e4d997ef20b86bb6750b8fb
  - >-
    Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 <
    ffa4f0be69656be1755090f02db38d49816585c6
  - >-
    Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 <
    d4cd32eb8bd2b0ffbdc7b1f3d82ce6a371f8f844
  - >-
    Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 <
    60dfd47929cd1e7070daa810d40ce538d888410d
  - >-
    Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 <
    6f7014237405e7f032b5c53a82d9eccf6161c291
  - Linux 4.8
published: '2026-09-04'
updated: '2026-10-19'
sourceUpdated: '2026-10-19T08:44:58.452Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-80864'
references:
  - url: 'https://git.kernel.org/stable/c/0136b528b753c5a56e4d997ef20b86bb6750b8fb'
  - url: 'https://git.kernel.org/stable/c/ffa4f0be69656be1755090f02db38d49816585c6'
  - url: 'https://git.kernel.org/stable/c/d4cd32eb8bd2b0ffbdc7b1f3d82ce6a371f8f844'
  - url: 'https://git.kernel.org/stable/c/60dfd47929cd1e7070daa810d40ce538d888410d'
  - url: 'https://git.kernel.org/stable/c/6f7014237405e7f032b5c53a82d9eccf6161c291'
tags:
  - cve.org
epss: 0.00156
epssPercentile: 0.04354
ingestedAt: '2026-10-19T09:16:01.491Z'
---

## Overview

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

RDMA/rxe: Fix responder UAF on IB_QP_MAX_DEST_RD_ATOMIC modify_qp

rxe_qp_from_attr() handles IB_QP_MAX_DEST_RD_ATOMIC outside the
IB_QP_STATE path, so it holds no state_lock and runs while the responder
task rxe_receiver() (recv_task on rxe_wq) is live. A modify_qp() setting
only that attribute calls free_rd_atomic_resources() then
alloc_rd_atomic_resources(), swapping qp->resp.resources[] while
rxe_prepare_res()/find_resource() walk it; free_rd_atomic_resources()
also leaves the cached pointer qp->resp.res dangling. A local
unprivileged user can race the free/realloc into a use-after-free in
rxe_receiver() (local DoS).

Drain recv_task around the swap with rxe_disable_task()/rxe_enable_task(),
as rxe_qp_reset() already does when tearing this array down, re-enabling
only after alloc_rd_atomic_resources() succeeds so the responder never
resumes against a NULL qp->resp.resources on the ENOMEM path. Also clear
qp->resp.res in free_rd_atomic_resources(), like the rxe_resp.c
completion paths.

Reproduced under KASAN; the slab-use-after-free in rxe_receiver() is gone.

## Affected

- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 0136b528b753c5a56e4d997ef20b86bb6750b8fb`
- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < ffa4f0be69656be1755090f02db38d49816585c6`
- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < d4cd32eb8bd2b0ffbdc7b1f3d82ce6a371f8f844`
- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 60dfd47929cd1e7070daa810d40ce538d888410d`
- `Linux >= 8700e3e7c4857d28ebaa824509934556da0b3e76 < 6f7014237405e7f032b5c53a82d9eccf6161c291`
- `Linux 4.8`

## Remediation

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