This is a note to let you know that I've just added the patch titled

USB: Gadget: dummy-hcd: Fix shift-out-of-bounds bug

to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From c318840fb2a42ce25febc95c4c19357acf1ae5ca Mon Sep 17 00:00:00 2001

From: Alan Stern stern@rowland.harvard.edu Date: Wed, 30 Dec 2020 11:20:44 -0500 Subject: USB: Gadget: dummy-hcd: Fix shift-out-of-bounds bug

The dummy-hcd driver was written under the assumption that all the parameters in URBs sent to its root hub would be valid. With URBs sent from userspace via usbfs, that assumption can be violated.

In particular, the driver doesn't fully check the port-feature values stored in the wValue entry of Clear-Port-Feature and Set-Port-Feature requests. Values that are too large can cause the driver to perform an invalid left shift of more than 32 bits. Ironically, two of those left shifts are unnecessary, because they implement Set-Port-Feature requests that hubs are not required to support, according to section 11.24.2.13 of the USB-2.0 spec.

This patch adds the appropriate checks for the port feature selector values and removes the unnecessary feature settings. It also rejects requests to set the TEST feature or to set or clear the INDICATOR and C_OVERCURRENT features, as none of these are relevant to dummy-hcd's root-hub emulation.

CC: stable@vger.kernel.org Reported-and-tested-by: syzbot+5925509f78293baa7331@syzkaller.appspotmail.com Signed-off-by: Alan Stern stern@rowland.harvard.edu Link: https://lore.kernel.org/r/20201230162044.GA727759@rowland.harvard.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/gadget/udc/dummy_hcd.c | 35 ++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/gadget/udc/dummy_hcd.c b/drivers/usb/gadget/udc/dummy_hcd.c index ab5e978b5052..1a953f44183a 100644 --- a/drivers/usb/gadget/udc/dummy_hcd.c +++ b/drivers/usb/gadget/udc/dummy_hcd.c @@ -2118,9 +2118,21 @@ static int dummy_hub_control( dum_hcd->port_status &= ~USB_PORT_STAT_POWER; set_link_state(dum_hcd); break; - default: + case USB_PORT_FEAT_ENABLE: + case USB_PORT_FEAT_C_ENABLE: + case USB_PORT_FEAT_C_SUSPEND: + /* Not allowed for USB-3 */ + if (hcd->speed == HCD_USB3) + goto error; + fallthrough; + case USB_PORT_FEAT_C_CONNECTION: + case USB_PORT_FEAT_C_RESET: dum_hcd->port_status &= ~(1 << wValue); set_link_state(dum_hcd); + break; + default: + /* Disallow INDICATOR and C_OVER_CURRENT */ + goto error; } break; case GetHubDescriptor: @@ -2281,18 +2293,17 @@ static int dummy_hub_control( */ dum_hcd->re_timeout = jiffies + msecs_to_jiffies(50); fallthrough; + case USB_PORT_FEAT_C_CONNECTION: + case USB_PORT_FEAT_C_RESET: + case USB_PORT_FEAT_C_ENABLE: + case USB_PORT_FEAT_C_SUSPEND: + /* Not allowed for USB-3, and ignored for USB-2 */ + if (hcd->speed == HCD_USB3) + goto error; + break; default: - if (hcd->speed == HCD_USB3) { - if ((dum_hcd->port_status & - USB_SS_PORT_STAT_POWER) != 0) { - dum_hcd->port_status |= (1 << wValue); - } - } else - if ((dum_hcd->port_status & - USB_PORT_STAT_POWER) != 0) { - dum_hcd->port_status |= (1 << wValue); - } - set_link_state(dum_hcd); + /* Disallow TEST, INDICATOR, and C_OVER_CURRENT */ + goto error; } break; case GetPortErrorCount: