[PATCH 4.18 18/34] usb: usbip: Fix BUG: KASAN: slab-out-of-bounds in vhci_hub_control()

Greg Kroah-Hartman
2018-11-09T07:47:12Z

From: Shuah Khan (Samsung OSG) <shuah@kernel.org>

commit 81f7567c51ad97668d1c3a48e8ecc482e64d4161 upstream.

vhci_hub_control() accesses port_status array with out of bounds port
value. Fix it to reference port_status[] only with a valid rhport value
when invalid_rhport flag is true.

The invalid_rhport flag is set early on after detecting in port value
is within the bounds or not.

The following is used reproduce the problem and verify the fix:
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14ed8ab6400000

Reported-by: syzbot+bccc1fe10b70fadc78d0@syzkaller.appspotmail.com
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/usb/usbip/vhci_hcd.c | 57 +++++++++++++++++++++++++++++++------------
1 file changed, 42 insertions(+), 15 deletions(-)

--- a/drivers/usb/usbip/vhci_hcd.c
+++ b/drivers/usb/usbip/vhci_hcd.c
@@ -318,8 +318,9 @@ static int vhci_hub_control(struct usb_h
struct vhci_hcd *vhci_hcd;
struct vhci *vhci;
int retval = 0;
- int rhport;
+ int rhport = -1;
unsigned long flags;
+ bool invalid_rhport = false;

u32 prev_port_status[VHCI_HC_PORTS];

@@ -334,9 +335,19 @@ static int vhci_hub_control(struct usb_h
usbip_dbg_vhci_rh("typeReq %x wValue %x wIndex %x\n", typeReq, wValue,
wIndex);

- if (wIndex > VHCI_HC_PORTS)
- pr_err("invalid port number %d\n", wIndex);
- rhport = wIndex - 1;
+ /*
+ * wIndex can be 0 for some request types (typeReq). rhport is
+ * in valid range when wIndex >= 1 and < VHCI_HC_PORTS.
+ *
+ * Reference port_status[] only with valid rhport when
+ * invalid_rhport is false.
+ */
+ if (wIndex < 1 || wIndex > VHCI_HC_PORTS) {
+ invalid_rhport = true;
+ if (wIndex > VHCI_HC_PORTS)
+ pr_err("invalid port number %d\n", wIndex);
+ } else
+ rhport = wIndex - 1;

vhci_hcd = hcd_to_vhci_hcd(hcd);
vhci = vhci_hcd->vhci;
@@ -345,8 +356,9 @@ static int vhci_hub_control(struct usb_h

/* store old status and compare now and old later */
if (usbip_dbg_flag_vhci_rh) {
- memcpy(prev_port_status, vhci_hcd->port_status,
- sizeof(prev_port_status));
+ if (!invalid_rhport)
+ memcpy(prev_port_status, vhci_hcd->port_status,
+ sizeof(prev_port_status));
}

switch (typeReq) {
@@ -354,8 +366,10 @@ static int vhci_hub_control(struct usb_h
usbip_dbg_vhci_rh(" ClearHubFeature\n");
break;
case ClearPortFeature:
- if (rhport < 0)
+ if (invalid_rhport) {
+ pr_err("invalid port number %d\n", wIndex);
goto error;
+ }
switch (wValue) {
case USB_PORT_FEAT_SUSPEND:
if (hcd->speed == HCD_USB3) {
@@ -415,9 +429,10 @@ static int vhci_hub_control(struct usb_h
break;
case GetPortStatus:
usbip_dbg_vhci_rh(" GetPortStatus port %x\n", wIndex);
- if (wIndex < 1) {
+ if (invalid_rhport) {
pr_err("invalid port number %d\n", wIndex);
retval = -EPIPE;
+ goto error;
}

/* we do not care about resume. */
@@ -513,16 +528,20 @@ static int vhci_hub_control(struct usb_h
goto error;
}

- if (rhport < 0)
+ if (invalid_rhport) {
+ pr_err("invalid port number %d\n", wIndex);
goto error;
+ }

vhci_hcd->port_status[rhport] |= USB_PORT_STAT_SUSPEND;
break;
case USB_PORT_FEAT_POWER:
usbip_dbg_vhci_rh(
" SetPortFeature: USB_PORT_FEAT_POWER\n");
- if (rhport < 0)
+ if (invalid_rhport) {
+ pr_err("invalid port number %d\n", wIndex);
goto error;
+ }
if (hcd->speed == HCD_USB3)
vhci_hcd->port_status[rhport] |= USB_SS_PORT_STAT_POWER;
else
@@ -531,8 +550,10 @@ static int vhci_hub_control(struct usb_h
case USB_PORT_FEAT_BH_PORT_RESET:
usbip_dbg_vhci_rh(
" SetPortFeature: USB_PORT_FEAT_BH_PORT_RESET\n");
- if (rhport < 0)
+ if (invalid_rhport) {
+ pr_err("invalid port number %d\n", wIndex);
goto error;
+ }
/* Applicable only for USB3.0 hub */
if (hcd->speed != HCD_USB3) {
pr_err("USB_PORT_FEAT_BH_PORT_RESET req not "
@@ -543,8 +564,10 @@ static int vhci_hub_control(struct usb_h
case USB_PORT_FEAT_RESET:
usbip_dbg_vhci_rh(
" SetPortFeature: USB_PORT_FEAT_RESET\n");
- if (rhport < 0)
+ if (invalid_rhport) {
+ pr_err("invalid port number %d\n", wIndex);
goto error;
+ }
/* if it's already enabled, disable */
if (hcd->speed == HCD_USB3) {
vhci_hcd->port_status[rhport] = 0;
@@ -565,8 +588,10 @@ static int vhci_hub_control(struct usb_h
default:
usbip_dbg_vhci_rh(" SetPortFeature: default %d\n",
wValue);
- if (rhport < 0)
+ if (invalid_rhport) {
+ pr_err("invalid port number %d\n", wIndex);
goto error;
+ }
if (hcd->speed == HCD_USB3) {
if ((vhci_hcd->port_status[rhport] &
USB_SS_PORT_STAT_POWER) != 0) {
@@ -608,7 +633,7 @@ error:
if (usbip_dbg_flag_vhci_rh) {
pr_debug("port %d\n", rhport);
/* Only dump valid port status */
- if (rhport >= 0) {
+ if (!invalid_rhport) {
dump_port_status_diff(prev_port_status[rhport],
vhci_hcd->port_status[rhport],
hcd->speed == HCD_USB3);
@@ -618,8 +643,10 @@ error:

spin_unlock_irqrestore(&vhci->lock, flags);

- if ((vhci_hcd->port_status[rhport] & PORT_C_MASK) != 0)
+ if (!invalid_rhport &&
+ (vhci_hcd->port_status[rhport] & PORT_C_MASK) != 0) {
usb_hcd_poll_rh_status(hcd);
+ }

return retval;
}