---
id: CVE-2026-53274
title: 'net/smc: fix sleep-inside-lock in __smc_setsockopt() causing local DoS'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/smc: fix sleep-inside-lock in __smc_setsockopt() causing local DoS

  A logic flaw in __smc_setsockopt() allows a local unprivileged user to
  cause a Denial of Service…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= a6a6fe27bab48f0d09a64b051e7bde432fcae081 <
    35a22117839602bb52283de08894c5a7dde92420
  - >-
    Linux >= a6a6fe27bab48f0d09a64b051e7bde432fcae081 <
    5d27d2ffe487df89ce28fda0410eafa05dbe03a0
  - >-
    Linux >= a6a6fe27bab48f0d09a64b051e7bde432fcae081 <
    89f6fbe0033c942cb790ffd53ca93a45eeaf1c91
  - >-
    Linux >= a6a6fe27bab48f0d09a64b051e7bde432fcae081 <
    dcd90f42a33e4220385f27b515183d0c91b2fc4a
  - >-
    Linux >= a6a6fe27bab48f0d09a64b051e7bde432fcae081 <
    94d286fa5eedc550d42bcb9c85416af8f77736ff
  - >-
    Linux >= a6a6fe27bab48f0d09a64b051e7bde432fcae081 <
    a3fdd924d88c30b9f488636ce0e4696012cf5511
  - Linux 5.18
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T16:24:48.310624Z'
published: '2026-06-25'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T16:34:17.070Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-53274'
references:
  - url: 'https://git.kernel.org/stable/c/35a22117839602bb52283de08894c5a7dde92420'
  - url: 'https://git.kernel.org/stable/c/5d27d2ffe487df89ce28fda0410eafa05dbe03a0'
  - url: 'https://git.kernel.org/stable/c/89f6fbe0033c942cb790ffd53ca93a45eeaf1c91'
  - url: 'https://git.kernel.org/stable/c/dcd90f42a33e4220385f27b515183d0c91b2fc4a'
  - url: 'https://git.kernel.org/stable/c/94d286fa5eedc550d42bcb9c85416af8f77736ff'
  - url: 'https://git.kernel.org/stable/c/a3fdd924d88c30b9f488636ce0e4696012cf5511'
tags:
  - cve.org
epss: 0.00121
epssPercentile: 0.01935
ingestedAt: '2026-11-06T16:57:43.259Z'
---

## Overview

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

net/smc: fix sleep-inside-lock in __smc_setsockopt() causing local DoS

A logic flaw in __smc_setsockopt() allows a local unprivileged user to
cause a Denial of Service (DoS) by holding the socket lock indefinitely.

The function __smc_setsockopt() calls copy_from_sockptr() while holding
lock_sock(sk). By passing a userfaultfd-monitored memory page (or
FUSE-backed memory on systems where unprivileged userfaultfd is disabled)
as the optval, an attacker can halt execution during the copy operation,
keeping the lock held.

Combined with asynchronous tear-down operations like shutdown(), this
exhausts the kernel wq (kworkers) and triggers the hung task watchdog.

[  240.123456] INFO: task kworker/u8:2 blocked for more than 120 seconds.
[  240.123489] Call Trace:
[  240.123501]  smc_shutdown+...
[  240.123512]  lock_sock_nested+...

This patch moves the user-space copy outside the lock_sock() critical
section to prevent the issue.

## Affected

- `Linux >= a6a6fe27bab48f0d09a64b051e7bde432fcae081 < 35a22117839602bb52283de08894c5a7dde92420`
- `Linux >= a6a6fe27bab48f0d09a64b051e7bde432fcae081 < 5d27d2ffe487df89ce28fda0410eafa05dbe03a0`
- `Linux >= a6a6fe27bab48f0d09a64b051e7bde432fcae081 < 89f6fbe0033c942cb790ffd53ca93a45eeaf1c91`
- `Linux >= a6a6fe27bab48f0d09a64b051e7bde432fcae081 < dcd90f42a33e4220385f27b515183d0c91b2fc4a`
- `Linux >= a6a6fe27bab48f0d09a64b051e7bde432fcae081 < 94d286fa5eedc550d42bcb9c85416af8f77736ff`
- `Linux >= a6a6fe27bab48f0d09a64b051e7bde432fcae081 < a3fdd924d88c30b9f488636ce0e4696012cf5511`
- `Linux 5.18`

## Remediation

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