2017-12-23 02:24:13

by Shuah Khan

Subject: [PATCH] usbip: fix vudc_rx: harden CMD_SUBMIT path to handle malicious input

Harden CMD_SUBMIT path to handle malicious input that could trigger
large memory allocations. Add checks to validate transfer_buffer_length
and number_of_packets to protect against bad input requesting for
unbounded memory allocations.

Signed-off-by: Shuah Khan <[email protected]>
---
drivers/usb/usbip/vudc_rx.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)

diff --git a/drivers/usb/usbip/vudc_rx.c b/drivers/usb/usbip/vudc_rx.c
index df1e30989148..1e8a23d92cb4 100644
--- a/drivers/usb/usbip/vudc_rx.c
+++ b/drivers/usb/usbip/vudc_rx.c
@@ -120,6 +120,25 @@ static int v_recv_cmd_submit(struct vudc *udc,
urb_p->new = 1;
urb_p->seqnum = pdu->base.seqnum;

+ if (urb_p->ep->type == USB_ENDPOINT_XFER_ISOC) {
+ /* validate packet size and number of packets */
+ unsigned int maxp, packets, bytes;
+
+ maxp = usb_endpoint_maxp(urb_p->ep->desc);
+ maxp *= usb_endpoint_maxp_mult(urb_p->ep->desc);
+ bytes = pdu->u.cmd_submit.transfer_buffer_length;
+ packets = DIV_ROUND_UP(bytes, maxp);
+
+ if (pdu->u.cmd_submit.number_of_packets < 0 ||
+ pdu->u.cmd_submit.number_of_packets > packets) {
+ dev_err(&udc->gadget.dev,
+ "CMD_SUBMIT: isoc invalid num packets %d\n",
+ pdu->u.cmd_submit.number_of_packets);
+ ret = -EMSGSIZE;
+ goto free_urbp;
+ }
+ }
+
ret = alloc_urb_from_cmd(&urb_p->urb, pdu, urb_p->ep->type);
if (ret) {
usbip_event_add(&udc->ud, VUDC_EVENT_ERROR_MALLOC);
--
2.14.1

2017-12-23 02:24:18

by Shuah Khan

Subject: [PATCH] usbip: vudc_tx: fix v_send_ret_submit() vulnerability to null xfer buffer

v_send_ret_submit() handles urb with a null transfer_buffer, when it
replays a packet with potential malicious data that could contain a
null buffer.

Add a check for the condition when actual_length > 0 and transfer_buffer
is null.

Signed-off-by: Shuah Khan <[email protected]>
---
drivers/usb/usbip/vudc_tx.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/usbip/vudc_tx.c b/drivers/usb/usbip/vudc_tx.c
index 1440ae0919ec..3ccb17c3e840 100644
--- a/drivers/usb/usbip/vudc_tx.c
+++ b/drivers/usb/usbip/vudc_tx.c
@@ -85,6 +85,13 @@ static int v_send_ret_submit(struct vudc *udc, struct urbp *urb_p)
memset(&pdu_header, 0, sizeof(pdu_header));
memset(&msg, 0, sizeof(msg));

+ if (urb->actual_length > 0 && !urb->transfer_buffer) {
+ dev_err(&udc->gadget.dev,
+ "urb: actual_length %d transfer_buffer null\n",
+ urb->actual_length);
+ return -1;
+ }
+
if (urb_p->type == USB_ENDPOINT_XFER_ISOC)
iovnum = 2 + urb->number_of_packets;
else
@@ -100,8 +107,8 @@ static int v_send_ret_submit(struct vudc *udc, struct urbp *urb_p)

/* 1. setup usbip_header */
setup_ret_submit_pdu(&pdu_header, urb_p);
- usbip_dbg_stub_tx("setup txdata seqnum: %d urb: %p\n",
- pdu_header.base.seqnum, urb);
+ usbip_dbg_stub_tx("setup txdata seqnum: %d\n",
+ pdu_header.base.seqnum);
usbip_header_correct_endian(&pdu_header, 1);

iov[iovnum].iov_base = &pdu_header;
--
2.14.1