CVE-2026-80983

Received Received - Intake

Socket Refcount Leak in Linux Kernel SMC

Publication date: 2026-09-11

Last updated on: 2026-09-14

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix socket refcount leak in smc_switch_conns() smc_switch_conns() takes a reference on the SMC socket before dropping lgr->conns_lock, so the connection stays alive while the CDC slot is fetched: sock_hold(&smc->sk); read_unlock_bh(&lgr->conns_lock); /* pre-fetch buffer outside of send_lock, might sleep */ rc = smc_cdc_get_free_slot(conn, to_lnk, &wr_buf, NULL, &pend); if (rc) goto err_out; The err_out label only drops the wr_tx link reference, so this early exit returns without the matching sock_put(). The second error exit is not affected, because sock_put() has already run by then. A leaked sk_refcnt means the smc_sock is never destroyed. Its send and receive buffers stay allocated, and for a user socket the reference held on the network namespace is never released, so the netns can no longer be torn down. smc_cdc_get_free_slot() fails when the target link goes down or when the connection has been killed while the switch is in progress. Both are reachable during the link failover this function implements, so the leak is triggered by the same hardware events that make smc_switch_conns() run in the first place. Restructure so there is a single sock_put() covering both outcomes, instead of adding a second one to the error path.

CVSS Scores

EPSS Scores

Probability:
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Meta Information

Published

2026-09-11

Last Modified

2026-09-14

Generated

2026-10-02

AI Q&A

2026-09-12

EPSS Evaluated

2026-10-01

NVD

CVE-2026-80983

EUVD

EUVD-2026-76306

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	*

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This vulnerability is a socket reference count leak in the Linux kernel's SMC (Socket Direct) module. The function smc_switch_conns() takes a reference on an SMC socket but fails to release it properly during error conditions. This causes the socket to never be destroyed, leaving allocated buffers and preventing the network namespace from being torn down.

Detection Guidance

This vulnerability is specific to the Linux kernel's SMC (Socket Direct) implementation and may not have direct detection commands. Monitor for kernel crashes, memory leaks, or network namespace issues. Check kernel logs for SMC-related errors or unexpected socket behavior.

Impact Analysis

The vulnerability can lead to resource exhaustion. The leaked socket prevents the network namespace from being destroyed, causing memory leaks. For user sockets, this also holds a reference to the network namespace, making it impossible to clean up properly.

Compliance Impact

This vulnerability causes a socket reference count leak in the Linux kernel's SMC (Socket Direct Protocol) implementation. The leaked reference prevents proper cleanup of network resources, including send and receive buffers, and may block network namespace destruction. This could lead to resource exhaustion or denial of service conditions, potentially impacting availability requirements in compliance standards like HIPAA and GDPR.

Mitigation Strategies

Apply the latest Linux kernel patches to address the socket refcount leak in smc_switch_conns(). Restart affected services or reboot the system after patching. Monitor network performance and kernel logs for signs of the issue.

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