CVE-2016-2185 (published 2016-05-02T10:59Z)

The ati_remote2_probe function in drivers/input/misc/ati_remote2.c in the Linux kernel before 4.5.1 allows physically proximate attackers to cause a denial of service (NULL pointer dereference and system crash) via a crafted endpoints value in a USB device descriptor.

Severity: MEDIUM
CVSS v2 base score: 4.9 (AV:L/AC:L/Au:N/C:N/I:N/A:C)
CVSS v3 base score: 4.6, MEDIUM (CVSS:3.0/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Weakness information:
cwe_id: NVD-CWE-Other
cwe_name: Other
description: NVD is only using a subset of CWE for mapping instead of the entire CWE, and the weakness type is not covered by that subset.
extended_description: Insufficient Information

Fix information:
repo_url: https://github.com/torvalds/linux
commit_details: repo_url: https://github.com/torvalds/linux
author: Vladis Dronov
author_date: 2016-03-23 11:53:46-07:00
msg: Input: ati_remote2 - fix crashes on detecting device with invalid descriptor

The ati_remote2 driver expects at least two interfaces with one
endpoint each. If given malicious descriptor that specify one
interface or no endpoints, it will crash in the probe function.
Ensure there is at least two interfaces and one endpoint for each
interface before using it.

The full disclosure: http://seclists.org/bugtraq/2016/Mar/90

Reported-by: Ralf Spenneberg <ralf@spenneberg.net>
Signed-off-by: Vladis Dronov <vdronov@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
repository: repo_url: https://github.com/torvalds/linux
repo_name: torvalds/linux
description: Linux kernel source tree
repo_language: C
owner: torvalds
file_changes: filename: ati_remote2.c
change_type: ModificationType.MODIFY
diff: @@ -817,26 +817,49 @@ static int ati_remote2_probe(struct usb_interface *interface, const struct usb_d
 
 	ar2->udev = udev;
 
+	/* Sanity check, first interface must have an endpoint */
+	if (alt->desc.bNumEndpoints < 1 || !alt->endpoint) {
+		dev_err(&interface->dev,
+			"%s(): interface 0 must have an endpoint\n", __func__);
+		r = -ENODEV;
+		goto fail1;
+	}
 	ar2->intf[0] = interface;
 	ar2->ep[0] = &alt->endpoint[0].desc;
 
+	/* Sanity check, the device must have two interfaces */
 	ar2->intf[1] = usb_ifnum_to_if(udev, 1);
+	if ((udev->actconfig->desc.bNumInterfaces < 2) || !ar2->intf[1]) {
+		dev_err(&interface->dev, "%s(): need 2 interfaces, found %d\n",
+			__func__, udev->actconfig->desc.bNumInterfaces);
+		r = -ENODEV;
+		goto fail1;
+	}
+
 	r = usb_driver_claim_interface(&ati_remote2_driver, ar2->intf[1], ar2);
 	if (r)
 		goto fail1;
+
+	/* Sanity check, second interface must have an endpoint */
 	alt = ar2->intf[1]->cur_altsetting;
+	if (alt->desc.bNumEndpoints < 1 || !alt->endpoint) {
+		dev_err(&interface->dev,
+			"%s(): interface 1 must have an endpoint\n", __func__);
+		r = -ENODEV;
+		goto fail2;
+	}
 	ar2->ep[1] = &alt->endpoint[0].desc;
 
 	r = ati_remote2_urb_init(ar2);
 	if (r)
-		goto fail2;
+		goto fail3;
 
 	ar2->channel_mask = channel_mask;
 	ar2->mode_mask = mode_mask;
 
 	r = ati_remote2_setup(ar2, ar2->channel_mask);
 	if (r)
-		goto fail2;
+		goto fail3;
 
 	usb_make_path(udev, ar2->phys, sizeof(ar2->phys));
 	strlcat(ar2->phys, "/input0", sizeof(ar2->phys));
@@ -845,11 +868,11 @@ static int ati_remote2_probe(struct usb_interface *interface, const struct usb_d
 
 	r = sysfs_create_group(&udev->dev.kobj, &ati_remote2_attr_group);
 	if (r)
-		goto fail2;
+		goto fail3;
 
 	r = ati_remote2_input_init(ar2);
 	if (r)
-		goto fail3;
+		goto fail4;
 
 	usb_set_intfdata(interface, ar2);
 
@@ -857,10 +880,11 @@ static int ati_remote2_probe(struct usb_interface *interface, const struct usb_d
 
 	return 0;
 
- fail3:
+ fail4:
 	sysfs_remove_group(&udev->dev.kobj, &ati_remote2_attr_group);
- fail2:
+ fail3:
 	ati_remote2_urb_cleanup(ar2);
+ fail2:
 	usb_driver_release_interface(&ati_remote2_driver, ar2->intf[1]);
  fail1:
 	kfree(ar2);

programming_language: C