---
id: CVE-2026-72222
title: 'sunrpc: pin svc_xprt across the asynchronous TLS handshake callback'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  sunrpc: pin svc_xprt across the asynchronous TLS handshake callback

  svc_tcp_handshake() stores the raw svc_xprt pointer in
  tls_handshake_args.ta_data and submits the r…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cvssSource: cna
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= b3cbf98e2fdf3cb147a95161560cd25987284330 <
    f3b55945dd99f29d83e1965d0141040a35262346
  - >-
    Linux >= b3cbf98e2fdf3cb147a95161560cd25987284330 <
    2d4f97d13fff91e0bc539216be88b884b544d49f
  - >-
    Linux >= b3cbf98e2fdf3cb147a95161560cd25987284330 <
    3f9ee75a97a769be258784c22b89657acb5ed9bd
  - >-
    Linux >= b3cbf98e2fdf3cb147a95161560cd25987284330 <
    083e9c2ec7e8bb13b79c9fd7b337abdd758ecc5f
  - >-
    Linux >= b3cbf98e2fdf3cb147a95161560cd25987284330 <
    4f988f3a2808fb659f3880c282041ff067acad78
  - Linux 6.4
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-10-16T18:44:02.358946Z'
published: '2026-08-15'
updated: '2026-10-16'
sourceUpdated: '2026-10-16T18:45:02.369Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-72222'
references:
  - url: 'https://git.kernel.org/stable/c/f3b55945dd99f29d83e1965d0141040a35262346'
  - url: 'https://git.kernel.org/stable/c/2d4f97d13fff91e0bc539216be88b884b544d49f'
  - url: 'https://git.kernel.org/stable/c/3f9ee75a97a769be258784c22b89657acb5ed9bd'
  - url: 'https://git.kernel.org/stable/c/083e9c2ec7e8bb13b79c9fd7b337abdd758ecc5f'
  - url: 'https://git.kernel.org/stable/c/4f988f3a2808fb659f3880c282041ff067acad78'
tags:
  - cve.org
epss: 0.00635
epssPercentile: 0.49341
ingestedAt: '2026-10-16T19:46:24.421Z'
---

## Overview

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

sunrpc: pin svc_xprt across the asynchronous TLS handshake callback

svc_tcp_handshake() stores the raw svc_xprt pointer in
tls_handshake_args.ta_data and submits the request through
tls_server_hello_x509(). The handshake core takes only
sock_hold(req->hr_sk); nothing references the embedding struct
svc_sock that svc_tcp_handshake_done() reaches via container_of().

Two close races leave the in-flight callback writing through a freed
svc_sock. svc_sock_free() calls tls_handshake_cancel() and discards
its return value: a false return means handshake_complete() has
already set HANDSHAKE_F_REQ_COMPLETED but hp_done() may not have
finished, yet svc_sock_free() proceeds to kfree(svsk). The
cancel-loser fall-through inside svc_tcp_handshake() itself produces
the same window: when wait_for_completion_interruptible_timeout()
returns <= 0 (timeout or signal) and tls_handshake_cancel() returns
false, the function does not drain, returns, and svc_handle_xprt()
calls svc_xprt_received(), which clears XPT_BUSY and can drop the
last reference. A concurrent close then runs svc_sock_free() while
svc_tcp_handshake_done() is still updating xpt_flags and walking
svsk->sk_handshake_done.

The corruption surfaces as set_bit/clear_bit RMW into the freed
xpt_flags slab slot and as complete_all() walking and writing the
freed wait_queue_head_t list embedded in sk_handshake_done -- a
slab-corruption primitive, not a benign read. The path is reachable
on any TLS-enabled NFS server whenever a connection close overlaps
the tlshd downcall delivery window; the interruptible wait means
signal delivery suffices, not just SVC_HANDSHAKE_TO expiry.

Take svc_xprt_get(xprt) immediately before tls_server_hello_x509()
so the in-flight callback owns its own reference. Release it on the
two edges where the callback is guaranteed not to fire -- submission
failure from tls_server_hello_x509() and a successful
tls_handshake_cancel() -- and at the tail of
svc_tcp_handshake_done() after complete_all().

[cel: rewrote commit message to describe the actual change]

## Affected

- `Linux >= b3cbf98e2fdf3cb147a95161560cd25987284330 < f3b55945dd99f29d83e1965d0141040a35262346`
- `Linux >= b3cbf98e2fdf3cb147a95161560cd25987284330 < 2d4f97d13fff91e0bc539216be88b884b544d49f`
- `Linux >= b3cbf98e2fdf3cb147a95161560cd25987284330 < 3f9ee75a97a769be258784c22b89657acb5ed9bd`
- `Linux >= b3cbf98e2fdf3cb147a95161560cd25987284330 < 083e9c2ec7e8bb13b79c9fd7b337abdd758ecc5f`
- `Linux >= b3cbf98e2fdf3cb147a95161560cd25987284330 < 4f988f3a2808fb659f3880c282041ff067acad78`
- `Linux 6.4`

## Remediation

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