On Thu, 19 Dec 2019, Johan Hovold wrote:

Amend the endpoint-descriptor sanity checks to detect all duplicate endpoint addresses in a configuration.

Commit 0a8fd1346254 ("USB: fix problems with duplicate endpoint addresses") added a check for duplicate endpoint addresses within a single alternate setting, but did not look for duplicate addresses in other interfaces.

The current check would also not detect all duplicate addresses when one endpoint is as a (bi-directional) control endpoint.

This specifically avoids overwriting the endpoint entries in struct usb_device when enabling a duplicate endpoint, something which could potentially lead to crashes or leaks, for example, when endpoints are later disabled.

Cc: stable stable@vger.kernel.org Signed-off-by: Johan Hovold johan@kernel.org

---

Exploiting this to trigger a crash probably requires a lot more malicious intent than the syzbot fuzzer currently possesses, but I think we need to plug this nonetheless.

Johan

This is a good improvement.

Acked-by: Alan Stern stern@rowland.harvard.edu

Alan Stern

drivers/usb/core/config.c | 70 ++++++++++++++++++++++++++++++++------- 1 file changed, 58 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c index 5f40117e68e7..21291950cc97 100644 --- a/drivers/usb/core/config.c +++ b/drivers/usb/core/config.c @@ -203,9 +203,58 @@ static const unsigned short super_speed_maxpacket_maxes[4] = { [USB_ENDPOINT_XFER_INT] = 1024, }; -static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum,

• int asnum, struct usb_host_interface *ifp, int num_ep,
• unsigned char *buffer, int size)

+static bool endpoint_is_duplicate(struct usb_endpoint_descriptor *e1,

• struct usb_endpoint_descriptor *e2)
  

+{

• if (e1->bEndpointAddress == e2->bEndpointAddress)

• return true;
  

• if (usb_endpoint_xfer_control(e1) || usb_endpoint_xfer_control(e2)) {

• if (usb_endpoint_num(e1) == usb_endpoint_num(e2))
  

• 	return true;
  

• }
• return false;

+}

+/*

• • Check for duplicate endpoint addresses in other interfaces and in the
• • altsetting currently being parsed.
• */

+static bool config_endpoint_is_duplicate(struct usb_host_config *config,

• int inum, int asnum, struct usb_endpoint_descriptor *d)
  

+{

• struct usb_endpoint_descriptor *epd;
• struct usb_interface_cache *intfc;
• struct usb_host_interface *alt;
• int i, j, k;
• for (i = 0; i < config->desc.bNumInterfaces; ++i) {

• intfc = config->intf_cache[i];
  

• for (j = 0; j < intfc->num_altsetting; ++j) {
  

• 	alt = &intfc->altsetting[j];
  

• 	if (alt->desc.bInterfaceNumber == inum &&
  

• 			alt->desc.bAlternateSetting != asnum)
  

• 		continue;
  

• 	for (k = 0; k < alt->desc.bNumEndpoints; ++k) {
  

• 		epd = &alt->endpoint[k].desc;
  

• 		if (endpoint_is_duplicate(epd, d))
  

• 			return true;
  

• 	}
  

• }
  

• }
• return false;

+}

+static int usb_parse_endpoint(struct device *ddev, int cfgno,

• struct usb_host_config *config, int inum, int asnum,
  

• struct usb_host_interface *ifp, int num_ep,
  

• unsigned char *buffer, int size)
  

{ unsigned char *buffer0 = buffer; struct usb_endpoint_descriptor *d; @@ -242,13 +291,10 @@ static int usb_parse_endpoint(struct device *ddev, int cfgno, int inum, goto skip_to_next_endpoint_or_interface_descriptor; /* Check for duplicate endpoint addresses */

• for (i = 0; i < ifp->desc.bNumEndpoints; ++i) {

• if (ifp->endpoint[i].desc.bEndpointAddress ==
  

•     d->bEndpointAddress) {
  

• 	dev_warn(ddev, "config %d interface %d altsetting %d has a duplicate endpoint with address 0x%X, skipping\n",
  

• 	    cfgno, inum, asnum, d->bEndpointAddress);
  

• 	goto skip_to_next_endpoint_or_interface_descriptor;
  

• }
  

• if (config_endpoint_is_duplicate(config, inum, asnum, d)) {

• dev_warn(ddev, "config %d interface %d altsetting %d has a duplicate endpoint with address 0x%X, skipping\n",
  

• 		cfgno, inum, asnum, d->bEndpointAddress);
  

• goto skip_to_next_endpoint_or_interface_descriptor;
  

  }

endpoint = &ifp->endpoint[ifp->desc.bNumEndpoints]; @@ -522,8 +568,8 @@ static int usb_parse_interface(struct device *ddev, int cfgno, if (((struct usb_descriptor_header *) buffer)->bDescriptorType == USB_DT_INTERFACE) break;

• retval = usb_parse_endpoint(ddev, cfgno, inum, asnum, alt,
  

•     num_ep, buffer, size);
  

• retval = usb_parse_endpoint(ddev, cfgno, config, inum, asnum,
  

• 		alt, num_ep, buffer, size);
  

  if (retval < 0) return retval; ++n;