Given the following code containing errors, provide Common Weakness Enumeration (CWE) identifiers and corresponding messages in JSON format. Each identified weakness should have a unique entry in the JSON array.
    Code: static int uvc_scan_chain_backward(struct uvc_video_chain *chain,
	struct uvc_entity **_entity)
{
	struct uvc_entity *entity = *_entity;
	struct uvc_entity *term;
	int id = -EINVAL, i;

	switch (UVC_ENTITY_TYPE(entity)) {
	case UVC_VC_EXTENSION_UNIT:
	case UVC_VC_PROCESSING_UNIT:
		id = entity->baSourceID[0];
		break;

	case UVC_VC_SELECTOR_UNIT:
		/* Single-input selector units are ignored. */
		if (entity->bNrInPins == 1) {
			id = entity->baSourceID[0];
			break;
		}

		if (uvc_trace_param & UVC_TRACE_PROBE)
			printk(KERN_CONT " <- IT");

		chain->selector = entity;
		for (i = 0; i < entity->bNrInPins; ++i) {
			id = entity->baSourceID[i];
			term = uvc_entity_by_id(chain->dev, id);
			if (term == NULL || !UVC_ENTITY_IS_ITERM(term)) {
				uvc_trace(UVC_TRACE_DESCR, "Selector unit %d "
					"input %d isn't connected to an "
					"input terminal\n", entity->id, i);
				return -1;
			}

			if (uvc_trace_param & UVC_TRACE_PROBE)
				printk(KERN_CONT " %d", term->id);

			list_add_tail(&term->chain, &chain->entities);
			uvc_scan_chain_forward(chain, term, entity);
		}

		if (uvc_trace_param & UVC_TRACE_PROBE)
			printk(KERN_CONT "\n");

		id = 0;
		break;

	case UVC_ITT_VENDOR_SPECIFIC:
	case UVC_ITT_CAMERA:
	case UVC_ITT_MEDIA_TRANSPORT_INPUT:
	case UVC_OTT_VENDOR_SPECIFIC:
	case UVC_OTT_DISPLAY:
	case UVC_OTT_MEDIA_TRANSPORT_OUTPUT:
	case UVC_TT_STREAMING:
		id = UVC_ENTITY_IS_OTERM(entity) ? entity->baSourceID[0] : 0;
		break;
	}

	if (id <= 0) {
		*_entity = NULL;
		return id;
	}

	entity = uvc_entity_by_id(chain->dev, id);
	if (entity == NULL) {
		uvc_trace(UVC_TRACE_DESCR, "Found reference to "
			"unknown entity %d.\n", id);
		return -EINVAL;
	}

	*_entity = entity;
	return 0;
} ; Sample JSON Format Confermily Expected output: "examples" => "cwe": "xxx"; "message": "xxx"
    
 'cwe': ['CWE-269'], 'message': 'media: uvcvideo: Avoid cyclic entity chains due to malformed USB descriptors

Way back in 2017, fuzzing the 4.14-rc2 USB stack with syzkaller kicked
up the following WARNING from the UVC chain scanning code:

  | list_add double add: new=ffff880069084010, prev=ffff880069084010,
  | next=ffff880067d22298.
  | ------------[ cut here ]------------
  | WARNING: CPU: 1 PID: 1846 at lib/list_debug.c:31 __list_add_valid+0xbd/0xf0
  | Modules linked in:
  | CPU: 1 PID: 1846 Comm: kworker/1:2 Not tainted
  | 4.14.0-rc2-42613-g1488251d1a98 #238
  | Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  | Workqueue: usb_hub_wq hub_event
  | task: ffff88006b01ca40 task.stack: ffff880064358000
  | RIP: 0010:__list_add_valid+0xbd/0xf0 lib/list_debug.c:29
  | RSP: 0018:ffff88006435ddd0 EFLAGS: 00010286
  | RAX: 0000000000000058 RBX: ffff880067d22298 RCX: 0000000000000000
  | RDX: 0000000000000058 RSI: ffffffff85a58800 RDI: ffffed000c86bbac
  | RBP: ffff88006435dde8 R08: 1ffff1000c86ba52 R09: 0000000000000000
  | R10: 0000000000000002 R11: 0000000000000000 R12: ffff880069084010
  | R13: ffff880067d22298 R14: ffff880069084010 R15: ffff880067d222a0
  | FS:  0000000000000000(0000) GS:ffff88006c900000(0000) knlGS:0000000000000000
  | CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  | CR2: 0000000020004ff2 CR3: 000000006b447000 CR4: 00000000000006e0
  | Call Trace:
  |  __list_add ./include/linux/list.h:59
  |  list_add_tail+0x8c/0x1b0 ./include/linux/list.h:92
  |  uvc_scan_chain_forward.isra.8+0x373/0x416
  | drivers/media/usb/uvc/uvc_driver.c:1471
  |  uvc_scan_chain drivers/media/usb/uvc/uvc_driver.c:1585
  |  uvc_scan_device drivers/media/usb/uvc/uvc_driver.c:1769
  |  uvc_probe+0x77f2/0x8f00 drivers/media/usb/uvc/uvc_driver.c:2104

Looking into the output from usbmon, the interesting part is the
following data packet:

  ffff880069c63e00 30710169 C Ci:1:002:0 0 143 = 09028f00 01030080
  00090403 00000e01 00000924 03000103 7c003328 010204db

If we drop the lead configuration and interface descriptors, we're left
with an output terminal descriptor describing a generic display:

  /* Output terminal descriptor */
  buf[0]	09
  buf[1]	24
  buf[2]	03	/* UVC_VC_OUTPUT_TERMINAL */
  buf[3]	00	/* ID */
  buf[4]	01	/* type == 0x0301 (UVC_OTT_DISPLAY) */
  buf[5]	03
  buf[6]	7c
  buf[7]	00	/* source ID refers to self! */
  buf[8]	33

The problem with this descriptor is that it is self-referential: the
source ID of 0 matches itself! This causes the 'struct uvc_entity'
representing the display to be added to its chain list twice during
'uvc_scan_chain()': once via 'uvc_scan_chain_entity()' when it is
processed directly from the 'dev->entities' list and then again
immediately afterwards when trying to follow the source ID in
'uvc_scan_chain_forward()'

Add a check before adding an entity to a chain list to ensure that the
entity is not already part of a chain.

Link: https://lore.kernel.org/linux-media/CAAeHK+z+Si69jUR+N-SjN9q4O+o5KFiNManqEa-PjUta7EOb7A@mail.gmail.com/

Cc: <stable@vger.kernel.org>
Fixes: c0efd232929c ("V4L/DVB (8145a): USB Video Class driver")
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>'