CVE-2026-64460: PCI/IOV: Skip VF Resizable BAR restore on read error

From: Greg Kroah-Hartman <[email protected]>

Description
===========

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

PCI/IOV: Skip VF Resizable BAR restore on read error

sriov_restore_vf_rebar_state() uses the VF Resizable BAR Control register
to decide how many VF BARs to restore (nbars) and which VF BAR each
iteration addresses (bar_idx). bar_idx indexes into dev->sriov->barsz[],
which has only PCI_SRIOV_NUM_BARS (6) entries.

When a device does not respond, config reads typically return
PCI_ERROR_RESPONSE (~0).  Both fields are 3 bits wide, so nbars and bar_idx
both evaluate to 7. The barsz[] access then goes out of bounds.  UBSAN
reports this as:

  UBSAN: array-index-out-of-bounds in drivers/pci/iov.c:948:51 index 7 is out of range for type 'resource_size_t [6]'

Observed on an NVIDIA RTX PRO 1000 GPU (GB207GLM) that stopped responding
during a failed GC6 power state exit. The subsequent pci_restore_state()
invoked sriov_restore_vf_rebar_state() while config reads returned
0xffffffff, triggering the splat.

Bail out if any VF Resizable BAR Control read returns PCI_ERROR_RESPONSE.
No further VF BARs are touched, which is safe because a config read that
returns PCI_ERROR_RESPONSE indicates the device is unreachable and
restoration is pointless. This mirrors the guard in
pci_restore_rebar_state().

The Linux kernel CVE team has assigned CVE-2026-64460 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 6.17 with commit 5a8f77e24a30bbce2fa57926f3dede84894fd10a and fixed in 6.18.39 with commit b77524621250407386f44c6eea7e5e4619ada1ce
	Issue introduced in 6.17 with commit 5a8f77e24a30bbce2fa57926f3dede84894fd10a and fixed in 7.1.4 with commit 55fd485e66d0ad5c762c23dba1461fe9c741cd96
	Issue introduced in 6.17 with commit 5a8f77e24a30bbce2fa57926f3dede84894fd10a and fixed in 7.2-rc1 with commit f34f1712229d71ce4286440fef12526fd4590b37

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-64460
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	drivers/pci/iov.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/b77524621250407386f44c6eea7e5e4619ada1ce
	https://git.kernel.org/stable/c/55fd485e66d0ad5c762c23dba1461fe9c741cd96
	https://git.kernel.org/stable/c/f34f1712229d71ce4286440fef12526fd4590b37