---
id: CVE-2026-46114
title: 'RDMA/rxe: Reject non-8-byte ATOMIC_WRITE payloads'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  RDMA/rxe: Reject non-8-byte ATOMIC_WRITE payloads

  atomic_write_reply() at drivers/infiniband/sw/rxe/rxe_resp.c
  unconditionally dereferences 8 bytes at payload_addr(pkt…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 034e285f8b99062a0cf29112e1232154a6a44aa5 <
    539cabb7b2d8ba70f55bba91db55faef11c2a6d7
  - >-
    Linux >= 034e285f8b99062a0cf29112e1232154a6a44aa5 <
    d415fce3fcde6d7aeea6c25362a395b905811452
  - >-
    Linux >= 034e285f8b99062a0cf29112e1232154a6a44aa5 <
    105bf79a23b85cf3a761d18a4f3e10ce88526bc1
  - >-
    Linux >= 034e285f8b99062a0cf29112e1232154a6a44aa5 <
    7ec1ed4747f5f99f8b797bb438c5efd36079fad5
  - >-
    Linux >= 034e285f8b99062a0cf29112e1232154a6a44aa5 <
    1114c87aa6f195cf07da55a27b2122ae26557b26
  - Linux 6.2
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-10-16T15:19:49.222043Z'
published: '2026-05-28'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T15:20:51.546Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-46114'
references:
  - url: 'https://git.kernel.org/stable/c/539cabb7b2d8ba70f55bba91db55faef11c2a6d7'
  - url: 'https://git.kernel.org/stable/c/d415fce3fcde6d7aeea6c25362a395b905811452'
  - url: 'https://git.kernel.org/stable/c/105bf79a23b85cf3a761d18a4f3e10ce88526bc1'
  - url: 'https://git.kernel.org/stable/c/7ec1ed4747f5f99f8b797bb438c5efd36079fad5'
  - url: 'https://git.kernel.org/stable/c/1114c87aa6f195cf07da55a27b2122ae26557b26'
tags:
  - cve.org
epss: 0.00467
epssPercentile: 0.39006
ingestedAt: '2026-10-16T17:24:46.707Z'
---

## Overview

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

RDMA/rxe: Reject non-8-byte ATOMIC_WRITE payloads

atomic_write_reply() at drivers/infiniband/sw/rxe/rxe_resp.c
unconditionally dereferences 8 bytes at payload_addr(pkt):

    value = *(u64 *)payload_addr(pkt);

check_rkey() previously accepted an ATOMIC_WRITE request with pktlen ==
resid == 0 because the length validation only compared pktlen against
resid. A remote initiator that sets the RETH length to 0 therefore reaches
atomic_write_reply() with a zero-byte logical payload, and the responder
reads sizeof(u64) bytes from past the logical end of the packet into
skb->head tailroom, then writes those 8 bytes into the attacker's MR via
rxe_mr_do_atomic_write(). That is a remote disclosure of 4 bytes of kernel
tailroom per probe (the other 4 bytes are the packet's own trailing ICRC).

IBA oA19-28 defines ATOMIC_WRITE as exactly 8 bytes. Anything else is
protocol-invalid. Hoist a strict length check into check_rkey() so the
responder never reaches the unchecked dereference, and keep the existing
WRITE-family length logic for the normal RDMA WRITE path.

Reproduced on mainline with an unmodified rxe driver: a sustained
zero-length ATOMIC_WRITE probe repeatedly leaks adjacent skb head-buffer
bytes into the attacker's MR, including recognisable kernel strings and
partial kernel-direct-map pointer words.  With this patch applied the
responder rejects the PDU and the MR stays all-zero.

## Affected

- `Linux >= 034e285f8b99062a0cf29112e1232154a6a44aa5 < 539cabb7b2d8ba70f55bba91db55faef11c2a6d7`
- `Linux >= 034e285f8b99062a0cf29112e1232154a6a44aa5 < d415fce3fcde6d7aeea6c25362a395b905811452`
- `Linux >= 034e285f8b99062a0cf29112e1232154a6a44aa5 < 105bf79a23b85cf3a761d18a4f3e10ce88526bc1`
- `Linux >= 034e285f8b99062a0cf29112e1232154a6a44aa5 < 7ec1ed4747f5f99f8b797bb438c5efd36079fad5`
- `Linux >= 034e285f8b99062a0cf29112e1232154a6a44aa5 < 1114c87aa6f195cf07da55a27b2122ae26557b26`
- `Linux 6.2`

## Remediation

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