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usb: host: max3421: Fix shift-out-of-bounds in max3421_hub_control()

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The `max3421_hub_control()` function handles USB hub class requests
to the virtual root hub. In the `default` branches of both the
`ClearPortFeature` and `SetPortFeature` switch statements, it modifies
`max3421_hcd->port_status` by left shifting 1 by the request's `value`
parameter. However, it does not validate whether this shift will exceed
the width of `port_status`.

So if a malicious userspace task with access to the root hub via
/dev/bus/usb/.../001 issues a USBDEVFS_CONTROL ioctl with `wValue`
greater than or equal to 32, the left shift operation invokes
shift-out-of-bounds undefined behavior. This results in arbitrary
bit corruption of `port_status`, including the normally-immutable
change bits, which can bypass internal state checks and confuse the
hub status.

Fix this by rejecting requests whose `value` exceeds the shift width
before performing the shift.

This issue was found using a KLEE-based symbolic execution tool for
kernel drivers that I'm currently developing.

Fixes: 2d53139f31 ("Add support for using a MAX3421E chip as a host driver.")
Signed-off-by: Seungjin Bae <eeodqql09@gmail.com>
Link: https://patch.msgid.link/20260518224901.1887013-1-eeodqql09@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Seungjin Bae 2026-05-18 18:49:00 -04:00 committed by Greg Kroah-Hartman
parent 8c22256bba
commit cff06b03b5
1 changed files with 4 additions and 0 deletions
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4
drivers/usb/host/max3421-hcd.c
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@ -1694,6 +1694,8 @@ max3421_hub_control(struct usb_hcd *hcd, u16 type_req, u16 value, u16 index,
!pdata->vbus_active_level);
fallthrough;
default:
if (value >= 32)
goto error;
max3421_hcd->port_status &= ~(1 << value);
}
break;
@ -1747,6 +1749,8 @@ max3421_hub_control(struct usb_hcd *hcd, u16 type_req, u16 value, u16 index,
max3421_reset_port(hcd);
fallthrough;
default:
if (value >= 32)
goto error;
if ((max3421_hcd->port_status & USB_PORT_STAT_POWER)
!= 0)
max3421_hcd->port_status |= (1 << value);