[PATCH 3.16 145/245] USB: core: fix check for duplicate endpoints

Ben Hutchings
2020-04-23T23:14:49Z

From: Johan Hovold <johan@kernel.org>

commit 3e4f8e21c4f27bcf30a48486b9dcc269512b79ff upstream.

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.

Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20191219161016.6695-1-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
drivers/usb/core/config.c | 70 ++++++++++++++++++++++++++++++++-------
1 file changed, 58 insertions(+), 12 deletions(-)

--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -169,9 +169,58 @@ static const unsigned short super_speed_
[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;
@@ -208,13 +257,10 @@ static int usb_parse_endpoint(struct dev
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];
@@ -481,8 +527,8 @@ static int usb_parse_interface(struct de
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;