On Mon, 11 Dec 2017, Greg KH wrote:
> From: Andrey Konovalov <andreyk...@google.com>
>
> When cleaning up the configurations, make sure we only free the number
> of configurations and interfaces that we could have allocated.
>
> Reported-by: Andrey Konovalov <andreyk...@google.com>
> Cc: stable <sta...@vger.kernel.org>
> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
>
> diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
> index 55b198ba629b..93b38471754e 100644
> --- a/drivers/usb/core/config.c
> +++ b/drivers/usb/core/config.c
> @@ -764,18 +764,21 @@ void usb_destroy_configuration(struct usb_device *dev)
> return;
>
> if (dev->rawdescriptors) {
> - for (i = 0; i < dev->descriptor.bNumConfigurations; i++)
> + for (i = 0; i < dev->descriptor.bNumConfigurations &&
> + i < USB_MAXCONFIG; i++)
> kfree(dev->rawdescriptors[i]);
>
> kfree(dev->rawdescriptors);
> dev->rawdescriptors = NULL;
> }
>
> - for (c = 0; c < dev->descriptor.bNumConfigurations; c++) {
> + for (c = 0; c < dev->descriptor.bNumConfigurations &&
> + c < USB_MAXCONFIG; c++) {
> struct usb_host_config *cf = &dev->config[c];
>
> kfree(cf->string);
> - for (i = 0; i < cf->desc.bNumInterfaces; i++) {
> + for (i = 0; i < cf->desc.bNumInterfaces &&
> + i < USB_MAXINTERFACES; i++) {
> if (cf->intf_cache[i])
> kref_put(&cf->intf_cache[i]->ref,
> usb_release_interface_cache);
None of these changes are necessary. The code is careful to reduce
dev->descriptor.bNumConfigurations and config->desc.bNumInterfaces when
necessary.
In usb_get_configuration() (line 806 on my system):
if (ncfg > USB_MAXCONFIG) {
dev_warn(ddev, "too many configurations: %d, "
"using maximum allowed: %d\n", ncfg, USB_MAXCONFIG);
dev->descriptor.bNumConfigurations = ncfg = USB_MAXCONFIG;
}
In usb_parse_configuration() (line 676 on my system):
if (n != nintf)
dev_warn(ddev, "config %d has %d interface%s, different from "
"the descriptor's value: %d\n",
cfgno, n, plural(n), nintf_orig);
else if (n == 0)
dev_warn(ddev, "config %d has no interfaces?\n", cfgno);
config->desc.bNumInterfaces = nintf = n;
Alan Stern
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