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 pin_rcv_pages(struct hfi1_filedata *fd, struct tid_user_buf *tidbuf)
{
	int pinned;
	unsigned int npages;
	unsigned long vaddr = tidbuf->vaddr;
	struct page **pages = NULL;
	struct hfi1_devdata *dd = fd->uctxt->dd;

	/* Get the number of pages the user buffer spans */
	npages = num_user_pages(vaddr, tidbuf->length);
	if (!npages)
		return -EINVAL;

	if (npages > fd->uctxt->expected_count) {
		dd_dev_err(dd, "Expected buffer too big\n");
		return -EINVAL;
	}

	/* Allocate the array of struct page pointers needed for pinning */
	pages = kcalloc(npages, sizeof(*pages), GFP_KERNEL);
	if (!pages)
		return -ENOMEM;

	/*
	 * Pin all the pages of the user buffer. If we can't pin all the
	 * pages, accept the amount pinned so far and program only that.
	 * User space knows how to deal with partially programmed buffers.
	 */
	if (!hfi1_can_pin_pages(dd, fd->mm, fd->tid_n_pinned, npages)) {
		kfree(pages);
		return -ENOMEM;
	}

	pinned = hfi1_acquire_user_pages(fd->mm, vaddr, npages, true, pages);
	if (pinned <= 0) {
		kfree(pages);
		return pinned;
	}
	tidbuf->pages = pages;
	tidbuf->npages = npages;
	fd->tid_n_pinned += pinned;
	return pinned;
} ; Sample JSON Format Confermily Expected output: "examples" => "cwe": "xxx"; "message": "xxx"
    
 'cwe': ['CWE-416'], 'message': 'IB/hfi1: Ensure correct mm is used at all times

Two earlier bug fixes have created a security problem in the hfi1
driver. One fix aimed to solve an issue where current->mm was not valid
when closing the hfi1 cdev. It attempted to do this by saving a cached
value of the current->mm pointer at file open time. This is a problem if
another process with access to the FD calls in via write() or ioctl() to
pin pages via the hfi driver. The other fix tried to solve a use after
free by taking a reference on the mm.

To fix this correctly we use the existing cached value of the mm in the
mmu notifier. Now we can check in the insert, evict, etc. routines that
current->mm matched what the notifier was registered for. If not, then
don't allow access. The register of the mmu notifier will save the mm
pointer.

Since in do_exit() the exit_mm() is called before exit_files(), which
would call our close routine a reference is needed on the mm. We rely on
the mmgrab done by the registration of the notifier, whereas before it was
explicit. The mmu notifier deregistration happens when the user context is
torn down, the creation of which triggered the registration.

Also of note is we do not do any explicit work to protect the interval
tree notifier. It doesn't seem that this is going to be needed since we
aren't actually doing anything with current->mm. The interval tree
notifier stuff still has a FIXME noted from a previous commit that will be
addressed in a follow on patch.

Cc: <stable@vger.kernel.org>
Fixes: e0cf75deab81 ("IB/hfi1: Fix mm_struct use after free")
Fixes: 3faa3d9a308e ("IB/hfi1: Make use of mm consistent")
Link: https://lore.kernel.org/r/20201125210112.104301.51331.stgit@awfm-01.aw.intel.com
Suggested-by: Jann Horn <jannh@google.com>
Reported-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@cornelisnetworks.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>'