From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Javier Martinez Canillas <javierm@redhat.com>

Date: Fri, 11 Dec 2020 19:19:21 +0100

Subject: [PATCH] usb: Avoid possible out-of-bound accesses caused by malicious

 devices

The maximum number of configurations and interfaces are fixed but there is

no out-of-bound checking to prevent a malicious USB device to report large

values for these and cause accesses outside the arrays' memory.

Fixes: CVE-2020-25647

Reported-by: Joseph Tartaro (IOActive)

Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>

Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

---

 grub-core/bus/usb/usb.c | 15 ++++++++++++---

 include/grub/usb.h      | 10 +++++++---

 2 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/grub-core/bus/usb/usb.c b/grub-core/bus/usb/usb.c

index 8da5e4c7491..7cb3cc230b2 100644

--- a/grub-core/bus/usb/usb.c

+++ b/grub-core/bus/usb/usb.c

@@ -75,6 +75,9 @@ grub_usb_controller_iterate (grub_usb_controller_iterate_hook_t hook,

 grub_usb_err_t

 grub_usb_clear_halt (grub_usb_device_t dev, int endpoint)

 {

+  if (endpoint >= GRUB_USB_MAX_TOGGLE)

+    return GRUB_USB_ERR_BADDEVICE;

+

   dev->toggle[endpoint] = 0;

   return grub_usb_control_msg (dev, (GRUB_USB_REQTYPE_OUT

 				     | GRUB_USB_REQTYPE_STANDARD

@@ -134,10 +137,10 @@ grub_usb_device_initialize (grub_usb_device_t dev)

     return err;

   descdev = &dev->descdev;

-  for (i = 0; i < 8; i++)

+  for (i = 0; i < GRUB_USB_MAX_CONF; i++)

     dev->config[i].descconf = NULL;

-  if (descdev->configcnt == 0)

+  if (descdev->configcnt == 0 || descdev->configcnt > GRUB_USB_MAX_CONF)

     {

       err = GRUB_USB_ERR_BADDEVICE;

       goto fail;

@@ -172,6 +175,12 @@ grub_usb_device_initialize (grub_usb_device_t dev)

       /* Skip the configuration descriptor.  */

       pos = dev->config[i].descconf->length;

+      if (dev->config[i].descconf->numif > GRUB_USB_MAX_IF)

+        {

+          err = GRUB_USB_ERR_BADDEVICE;

+          goto fail;

+        }

+

       /* Read all interfaces.  */

       for (currif = 0; currif < dev->config[i].descconf->numif; currif++)

 	{

@@ -217,7 +226,7 @@ grub_usb_device_initialize (grub_usb_device_t dev)

  fail:

-  for (i = 0; i < 8; i++)

+  for (i = 0; i < GRUB_USB_MAX_CONF; i++)

     grub_free (dev->config[i].descconf);

   return err;

diff --git a/include/grub/usb.h b/include/grub/usb.h

index 11d96481ff6..f26b89b7fd4 100644

--- a/include/grub/usb.h

+++ b/include/grub/usb.h

@@ -23,6 +23,10 @@

 #include <grub/usbdesc.h>

 #include <grub/usbtrans.h>

+#define GRUB_USB_MAX_CONF    8

+#define GRUB_USB_MAX_IF      32

+#define GRUB_USB_MAX_TOGGLE  256

+

 typedef struct grub_usb_device *grub_usb_device_t;

 typedef struct grub_usb_controller *grub_usb_controller_t;

 typedef struct grub_usb_controller_dev *grub_usb_controller_dev_t;

@@ -167,7 +171,7 @@ struct grub_usb_configuration

   struct grub_usb_desc_config *descconf;

   /* Interfaces associated to this configuration.  */

-  struct grub_usb_interface interf[32];

+  struct grub_usb_interface interf[GRUB_USB_MAX_IF];

 };

 struct grub_usb_hub_port

@@ -191,7 +195,7 @@ struct grub_usb_device

   struct grub_usb_controller controller;

   /* Device configurations (after opening the device).  */

-  struct grub_usb_configuration config[8];

+  struct grub_usb_configuration config[GRUB_USB_MAX_CONF];

   /* Device address.  */

   int addr;

@@ -203,7 +207,7 @@ struct grub_usb_device

   int initialized;

   /* Data toggle values (used for bulk transfers only).  */

-  int toggle[256];

+  int toggle[GRUB_USB_MAX_TOGGLE];

   /* Used by libusb wrapper.  Schedulded for removal. */

   void *data;