---
id: CVE-2026-53051
title: 'PCI: tegra194: Fix CBB timeout caused by DBI access before core power-on'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  PCI: tegra194: Fix CBB timeout caused by DBI access before core power-on

  When PERST# is deasserted twice (assert -> deassert -> assert -> deassert),
  a CBB (Control Bac…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 72034050ccf4202cd6558b0afd2474f756ea3b9b <
    010983063a806720b45778d191335f8ea864fea3
  - >-
    Linux >= 40e2125381dc11379112485e3eefdd25c6df5375 <
    b059a41bdd5b202b2b9d7708403fb43c69689e53
  - >-
    Linux >= 40e2125381dc11379112485e3eefdd25c6df5375 <
    ce899f9c019591b73ef84b9afa332ed53beece25
  - >-
    Linux >= 40e2125381dc11379112485e3eefdd25c6df5375 <
    34b3eef48d980cd37b876e128bbf314f69fb5d70
  - Linux 70212c2300971506e986d95000d2745529cac9d7
  - Linux >= 6.12.2 < 6.12.91
  - Linux >= 6.11.11 < 6.12
  - Linux 6.13
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-06T16:17:18.206478Z'
published: '2026-06-24'
updated: '2026-11-06'
sourceUpdated: '2026-11-06T16:23:57.088Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-53051'
references:
  - url: 'https://git.kernel.org/stable/c/010983063a806720b45778d191335f8ea864fea3'
  - url: 'https://git.kernel.org/stable/c/b059a41bdd5b202b2b9d7708403fb43c69689e53'
  - url: 'https://git.kernel.org/stable/c/ce899f9c019591b73ef84b9afa332ed53beece25'
  - url: 'https://git.kernel.org/stable/c/34b3eef48d980cd37b876e128bbf314f69fb5d70'
tags:
  - cve.org
epss: 0.00162
epssPercentile: 0.05386
ingestedAt: '2026-11-06T16:57:43.305Z'
---

## Overview

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

PCI: tegra194: Fix CBB timeout caused by DBI access before core power-on

When PERST# is deasserted twice (assert -> deassert -> assert -> deassert),
a CBB (Control Backbone) timeout occurs at DBI register offset 0x8bc
(PCIE_MISC_CONTROL_1_OFF). This happens because pci_epc_deinit_notify()
and dw_pcie_ep_cleanup() are called before reset_control_deassert() powers
on the controller core.

The call chain that causes the timeout:

  pex_ep_event_pex_rst_deassert()
    pci_epc_deinit_notify()
      pci_epf_test_epc_deinit()
        pci_epf_test_clear_bar()
          pci_epc_clear_bar()
            dw_pcie_ep_clear_bar()
              __dw_pcie_ep_reset_bar()
                dw_pcie_dbi_ro_wr_en()      <- Accesses 0x8bc DBI register
    reset_control_deassert(pcie->core_rst)  <- Core powered on HERE

The DBI registers, including PCIE_MISC_CONTROL_1_OFF (0x8bc), are only
accessible after the controller core is powered on via
reset_control_deassert(pcie->core_rst). Accessing them before this point
results in a CBB timeout because the hardware is not yet operational.

Fix this by moving pci_epc_deinit_notify() and dw_pcie_ep_cleanup() to
after reset_control_deassert(pcie->core_rst), ensuring the controller is
fully powered on before any DBI register accesses occur.

## Affected

- `Linux >= 72034050ccf4202cd6558b0afd2474f756ea3b9b < 010983063a806720b45778d191335f8ea864fea3`
- `Linux >= 40e2125381dc11379112485e3eefdd25c6df5375 < b059a41bdd5b202b2b9d7708403fb43c69689e53`
- `Linux >= 40e2125381dc11379112485e3eefdd25c6df5375 < ce899f9c019591b73ef84b9afa332ed53beece25`
- `Linux >= 40e2125381dc11379112485e3eefdd25c6df5375 < 34b3eef48d980cd37b876e128bbf314f69fb5d70`
- `Linux 70212c2300971506e986d95000d2745529cac9d7`
- `Linux >= 6.12.2 < 6.12.91`
- `Linux >= 6.11.11 < 6.12`
- `Linux 6.13`

## Remediation

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