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    Subject[PATCH 3.16 145/245] USB: core: fix check for duplicate endpoints
    3.16.83-rc1 review patch.  If anyone has any objections, please let me know.

    ------------------

    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;
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