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

Overview

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().

Affected

• Linux >= 5a8f77e24a30bbce2fa57926f3dede84894fd10a < b77524621250407386f44c6eea7e5e4619ada1ce
• Linux >= 5a8f77e24a30bbce2fa57926f3dede84894fd10a < 55fd485e66d0ad5c762c23dba1461fe9c741cd96
• Linux >= 5a8f77e24a30bbce2fa57926f3dede84894fd10a < f34f1712229d71ce4286440fef12526fd4590b37
• Linux 6.17

Remediation

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