Description
In the Linux kernel, the following vulnerability has been resolved:
usb: xhci: bail out of setup if the controller is inaccessible
xhci_gen_setup() locates the operational registers using the capability
length read from the very first register:
xhci->op_regs = hcd->regs +
HC_LENGTH(readl(&xhci->cap_regs->hc_capbase));
If the controller is dead or has dropped off the bus, that read returns
~0, HC_LENGTH() truncates it to 0xff, and op_regs ends up 0xff bytes
past the page-aligned MMIO base, i.e. unaligned. The first access
through it, xhci_halt() -> xhci_handshake() reading op_regs->status, is
then an unaligned readl() on device memory. arm64 faults on unaligned
device accesses, so instead of xhci_handshake() catching the all-ones
value and returning -ENODEV, setup oopses:
xhci-pci-renesas 0005:08:00.0: Unable to change power state from D3cold to D0, device inaccessible
xhci-pci-renesas 0005:08:00.0: xHCI Host Controller
xhci-pci-renesas 0005:08:00.0: new USB bus registered, assigned bus number 1
Unable to handle kernel paging request at virtual address ffff80030a770103
ESR = 0x0000000096000021
FSC = 0x21: alignment fault
Internal error: Oops: 0000000096000021 [#1] SMP
pc : xhci_halt [xhci_hcd]
Call trace:
xhci_halt
xhci_gen_setup
xhci_pci_setup
usb_add_hcd
usb_hcd_pci_probe
xhci_pci_common_probe
xhci_pci_renesas_probe
This was hit with a Renesas uPD720201 that failed to power up ("Unable
to change power state from D3cold to D0, device inaccessible") yet still
reached the HCD probe path.
Read the capability register once, and if it reads back the all-ones
value (as xhci_handshake() and xhci_reset() already test for), abort
setup with -ENODEV before op_regs is derived from it. Reading it once
also avoids re-reading a register that may change under a concurrent
hot-removal.
usb: xhci: bail out of setup if the controller is inaccessible
xhci_gen_setup() locates the operational registers using the capability
length read from the very first register:
xhci->op_regs = hcd->regs +
HC_LENGTH(readl(&xhci->cap_regs->hc_capbase));
If the controller is dead or has dropped off the bus, that read returns
~0, HC_LENGTH() truncates it to 0xff, and op_regs ends up 0xff bytes
past the page-aligned MMIO base, i.e. unaligned. The first access
through it, xhci_halt() -> xhci_handshake() reading op_regs->status, is
then an unaligned readl() on device memory. arm64 faults on unaligned
device accesses, so instead of xhci_handshake() catching the all-ones
value and returning -ENODEV, setup oopses:
xhci-pci-renesas 0005:08:00.0: Unable to change power state from D3cold to D0, device inaccessible
xhci-pci-renesas 0005:08:00.0: xHCI Host Controller
xhci-pci-renesas 0005:08:00.0: new USB bus registered, assigned bus number 1
Unable to handle kernel paging request at virtual address ffff80030a770103
ESR = 0x0000000096000021
FSC = 0x21: alignment fault
Internal error: Oops: 0000000096000021 [#1] SMP
pc : xhci_halt [xhci_hcd]
Call trace:
xhci_halt
xhci_gen_setup
xhci_pci_setup
usb_add_hcd
usb_hcd_pci_probe
xhci_pci_common_probe
xhci_pci_renesas_probe
This was hit with a Renesas uPD720201 that failed to power up ("Unable
to change power state from D3cold to D0, device inaccessible") yet still
reached the HCD probe path.
Read the capability register once, and if it reads back the all-ones
value (as xhci_handshake() and xhci_reset() already test for), abort
setup with -ENODEV before op_regs is derived from it. Reading it once
also avoids re-reading a register that may change under a concurrent
hot-removal.
Published:
2026-09-04
Score:
n/a
EPSS:
n/a
KEV:
No
Impact:
n/a
Action:
n/a
Analysis
No analysis available yet.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
||||||||||||||||||
| Linux | Linux | affected |
|
No data.
No data.
No data available yet.
Remediation
No remediation available yet.
Tracking
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Advisories
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References
History
Fri, 04 Sep 2026 16:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: usb: xhci: bail out of setup if the controller is inaccessible xhci_gen_setup() locates the operational registers using the capability length read from the very first register: xhci->op_regs = hcd->regs + HC_LENGTH(readl(&xhci->cap_regs->hc_capbase)); If the controller is dead or has dropped off the bus, that read returns ~0, HC_LENGTH() truncates it to 0xff, and op_regs ends up 0xff bytes past the page-aligned MMIO base, i.e. unaligned. The first access through it, xhci_halt() -> xhci_handshake() reading op_regs->status, is then an unaligned readl() on device memory. arm64 faults on unaligned device accesses, so instead of xhci_handshake() catching the all-ones value and returning -ENODEV, setup oopses: xhci-pci-renesas 0005:08:00.0: Unable to change power state from D3cold to D0, device inaccessible xhci-pci-renesas 0005:08:00.0: xHCI Host Controller xhci-pci-renesas 0005:08:00.0: new USB bus registered, assigned bus number 1 Unable to handle kernel paging request at virtual address ffff80030a770103 ESR = 0x0000000096000021 FSC = 0x21: alignment fault Internal error: Oops: 0000000096000021 [#1] SMP pc : xhci_halt [xhci_hcd] Call trace: xhci_halt xhci_gen_setup xhci_pci_setup usb_add_hcd usb_hcd_pci_probe xhci_pci_common_probe xhci_pci_renesas_probe This was hit with a Renesas uPD720201 that failed to power up ("Unable to change power state from D3cold to D0, device inaccessible") yet still reached the HCD probe path. Read the capability register once, and if it reads back the all-ones value (as xhci_handshake() and xhci_reset() already test for), abort setup with -ENODEV before op_regs is derived from it. Reading it once also avoids re-reading a register that may change under a concurrent hot-removal. | |
| Title | usb: xhci: bail out of setup if the controller is inaccessible | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-04T15:55:15.491Z
Reserved: 2026-08-26T14:34:25.798Z
Link: CVE-2026-80861
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-04T16:18:15.290
Modified: 2026-09-04T16:18:15.290
Link: CVE-2026-80861
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.