---
id: "CVE-2026-99032"
kind: "vulnerability"
aliases: ["CVE-2026-99032"]
title: "Linux kernel SMC: getsockname use-after-free when link group terminates"
severity: "unknown"
cvss: null
epss: 0.00209
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["linux-kernel", "multi-tenant", "runtime", "self-hosted"]
not_affected_if: ["no-smc-sockets", "smc-module-not-loaded"]
published_at: "2026-10-23T13:17:26+00:00"
first_seen_at: "2026-10-23T21:57:33+00:00"
updated_at: "2026-10-25T12:38:50+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99032", "first_seen_at": "2026-10-23T21:57:33+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-99032", "first_seen_at": "2026-10-25T12:38:50+00:00"}]
---

# Linux kernel SMC: getsockname use-after-free when link group terminates

A race in the Linux kernel's SMC socket code lets a getsockname() call touch a CLC socket that another worker has already released. The result is a use-after-free or NULL dereference in kernel memory, which can crash the machine or be turned into code execution by a local user.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- `uname -r` and compare against the fixed kernel builds in your distribution's advisory
- `lsmod | grep smc` or `grep -i smc /proc/net/protocols` to see whether the SMC protocol is loaded
- `sysctl net.smc.autocorking_size` to confirm the SMC module is present (unknown if the sources do not say otherwise)

## Fix

- Update the Linux kernel to a build that includes the upstream fix 'net/smc: protect clcsock lifetime in smc_getname'
- Until patched, unload the SMC module with `modprobe -r smc_diag smc` where it is not in use (unknown if the sources give a supported workaround)

## Timeline

- 2026-10-23T21:57:33+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99032
- 2026-10-25T12:38:50+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-99032

## From the sources

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

net/smc: protect clcsock lifetime in smc_getname

smc_getname() dereferences smc->clcsock without holding
clcsock_release_lock. Link-group termination can release the CLC socket
through smc_close_active_abort() while the SMC socket is still open,
for example after shutdown(SHUT_WR).

A getsockname() caller can load smc->clcsock, then the termination worker
can clear the pointer and call sock_release() before the caller accesses
clcsock->ops or invokes getname(). This causes a use-after-free; if the
worker clears the pointer before the load, it causes a NULL dereference.
The syscall's file reference keeps the SMC socket alive but does not
prevent asynchronous release of its CLC socket.

KASAN reported the following with test-only timing instrumentation:

  BUG: KASAN: slab-use-after-free in smc_getname+0x19e/0x1b0
  Read of size 8 at addr ffff888109abb4e0 by task poc/103
  Call Trace:
   smc_getname+0x19e/0x1b0
   do_getsockname+0xe5/0x170
   __sys_getsockname+0x8c/0x100

  Allocated by task 95:
   sock_alloc_inode+0x1e/0x280
   sock_alloc+0x3d/0x240
   __sock_create+0x7e/0x430
   smc_create+0x121/0x240

  Freed by task 0:
   kmem_cache_free+0xcc/0x340
   rcu_core+0x50a/0x1850

  Last potentially related work creation:
   evict+0x446/0x6c0
   smc_clcsock_release+0xa8/0xd0
   smc_close_active_abort+0x26a/0x3a0
   __smc_lgr_terminate.part.0+0x137/0x2e0

Hold clcsock_release_lock across the pointer check and the getname()
callback to serialize with smc_clcsock_release(). Return -EBADF if the
CLC socket has already been released, preserving the existing peer
state check and the callback's return value otherwise.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_