---
id: CVE-2026-64071
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nvme-pci: fix use-after-free in nvme_free_host_mem()

  nvme_free_host_mem() frees dev->hmb_sgt via dma_free_noncontiguous()
  but never clears the pointer afterward
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  nvme-pci: fix use-after-free in nvme_free_host_mem()

  nvme_free_host_mem() frees dev->hmb_sgt via dma_free_noncontiguous()
  but never clears the pointer afterward.  This…
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-416
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 6.13, < 6.18.34'
  - 'linux_kernel >= 6.19, < 7.0.11'
  - linux_kernel = 7.1
patched:
  - linux_kernel 7.0.11
published: '2026-07-19'
updated: '2026-09-03'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64071'
references:
  - url: 'https://git.kernel.org/stable/c/7c89f474005d8377525d2991930b7432ee193a52'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/9525e3a6fbb1d126a22ab2ee86ddea25af581a7c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b35a13036755c5803168a7cb93bc66035c3e65b8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00133
epssPercentile: 0.03186
ingestedAt: '2026-09-04T04:14:25.788Z'
---

## Overview

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

nvme-pci: fix use-after-free in nvme_free_host_mem()

nvme_free_host_mem() frees dev->hmb_sgt via dma_free_noncontiguous()
but never clears the pointer afterward.  This leads to a use-after-free
if nvme_free_host_mem() is called twice in the same error path.

This can happen during nvme_probe() when nvme_setup_host_mem() succeeds
in allocating the HMB (setting dev->hmb_sgt) but nvme_set_host_mem()
fails with an I/O error:

  nvme_setup_host_mem()
    nvme_alloc_host_mem_single()   -> sets dev->hmb_sgt
    nvme_set_host_mem()            -> fails with -EIO
    nvme_free_host_mem()           -> frees hmb_sgt, but does NOT NULL it
    return error

  nvme_probe() error path:
    nvme_free_host_mem()           -> dev->hmb_sgt is stale, use-after-free

The second call dereferences the freed sgt, causing a NULL pointer
dereference in iommu_dma_free_noncontiguous() when it accesses
sgt->sgl->dma_address (the backing memory has been freed and zeroed).

This is reproducible on Thunderbolt-attached NVMe devices (e.g., OWC
Envoy Express behind a Dell WD22TB4 dock) where the device intermittently
returns I/O errors during HMB setup due to PCIe link instability.

 BUG: kernel NULL pointer dereference, address: 0000000000000010
 RIP: 0010:iommu_dma_free_noncontiguous+0x22/0x80
 Call Trace:
  <TASK>
  dma_free_noncontiguous+0x3b/0x130
  nvme_free_host_mem+0x30/0xf0 [nvme]
  nvme_probe.cold+0xcc/0x275 [nvme]
  local_pci_probe+0x43/0xa0
  pci_device_probe+0xeea/0x290
  really_probe+0xf9/0x3b0
  __driver_probe_device+0x8b/0x170
  driver_probe_device+0x24/0xd0
  __driver_attach_async_helper+0x6b/0x110
  async_run_entry_fn+0x37/0x170
  process_one_work+0x1ac/0x3d0
  worker_thread+0x1b8/0x360
  kthread+0xf7/0x130
  ret_from_fork+0x2d8/0x3a0
  ret_from_fork_asm+0x1a/0x30
  </TASK>

Fix this by setting dev->hmb_sgt to NULL after freeing it, so the
second call takes the multi-descriptor path which safely handles the
already-cleaned-up state.

## Affected

- `linux_kernel >= 6.13, < 6.18.34`
- `linux_kernel >= 6.19, < 7.0.11`
- `linux_kernel = 7.1`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.11`