[PATCH 2/2] usbip: vhci_hcd: reduce CONFIG_USBIP_VHCI_NR_HCS upper bound to 32

Adrian Wowk
2026-04-14T01:01:03Z

Each VHCI HC instance registers two USB buses (one HS, one SS).
USB_MAXBUS in drivers/usb/core/hcd.c is hard-coded to 64, giving an
effective maximum of 32 VHCI HC instances (32 * 2 = 64 buses).

The Kconfig range for USBIP_VHCI_NR_HCS currently allows up to 128,
which will cause probe failures for any HC instance beyond the 32nd.
These probe failures trigger the NULL pointer dereference fixed in the
previous commit.

Reduce the upper bound to 32 to reflect the real maximum imposed by
USB_MAXBUS. Note that probe failures can still occur below this limit
if real hardware has already claimed enough USB bus numbers, making
the NULL check fix necessary regardless.

Signed-off-by: Adrian Wowk <dev@adrianwowk.com>
---
drivers/usb/usbip/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/usbip/Kconfig b/drivers/usb/usbip/Kconfig
index b9f94e2e278..50945b6fae1 100644
--- a/drivers/usb/usbip/Kconfig
+++ b/drivers/usb/usbip/Kconfig
@@ -40,7 +40,7 @@ config USBIP_VHCI_HC_PORTS

config USBIP_VHCI_NR_HCS
int "Number of USB/IP virtual host controllers"
- range 1 128
+ range 1 32
default 1
depends on USBIP_VHCI_HCD
help
--
2.53.0