build_path_from_dentry(struct dentry *direntry)
{
	struct dentry *temp;
	int namelen;
	int dfsplen;
	char *full_path;
	char dirsep;
	struct cifs_sb_info *cifs_sb = CIFS_SB(direntry->d_sb);
	struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
	unsigned seq;

	dirsep = CIFS_DIR_SEP(cifs_sb);
	if (tcon->Flags & SMB_SHARE_IS_IN_DFS)
		dfsplen = strnlen(tcon->treeName, MAX_TREE_SIZE + 1);
	else
		dfsplen = 0;
cifs_bp_rename_retry:
	namelen = dfsplen;
	seq = read_seqbegin(&rename_lock);
	rcu_read_lock();
	for (temp = direntry; !IS_ROOT(temp);) {
		namelen += (1 + temp->d_name.len);
		temp = temp->d_parent;
		if (temp == NULL) {
			cERROR(1, "corrupt dentry");
			rcu_read_unlock();
			return NULL;
		}
	}
	rcu_read_unlock();

	full_path = kmalloc(namelen+1, GFP_KERNEL);
	if (full_path == NULL)
		return full_path;
	full_path[namelen] = 0;	/* trailing null */
	rcu_read_lock();
	for (temp = direntry; !IS_ROOT(temp);) {
		spin_lock(&temp->d_lock);
		namelen -= 1 + temp->d_name.len;
		if (namelen < 0) {
			spin_unlock(&temp->d_lock);
			break;
		} else {
			full_path[namelen] = dirsep;
			strncpy(full_path + namelen + 1, temp->d_name.name,
				temp->d_name.len);
			cFYI(0, "name: %s", full_path + namelen);
		}
		spin_unlock(&temp->d_lock);
		temp = temp->d_parent;
		if (temp == NULL) {
			cERROR(1, "corrupt dentry");
			rcu_read_unlock();
			kfree(full_path);
			return NULL;
		}
	}
	rcu_read_unlock();
	if (namelen != dfsplen || read_seqretry(&rename_lock, seq)) {
		cFYI(1, "did not end path lookup where expected. namelen=%d "
			"dfsplen=%d", namelen, dfsplen);
		/* presumably this is only possible if racing with a rename
		of one of the parent directories  (we can not lock the dentries
		above us to prevent this, but retrying should be harmless) */
		kfree(full_path);
		goto cifs_bp_rename_retry;
	}
	/* DIR_SEP already set for byte  0 / vs \ but not for
	   subsequent slashes in prepath which currently must
	   be entered the right way - not sure if there is an alternative
	   since the '\' is a valid posix character so we can not switch
	   those safely to '/' if any are found in the middle of the prepath */
	/* BB test paths to Windows with '/' in the midst of prepath */

	if (dfsplen) {
		strncpy(full_path, tcon->treeName, dfsplen);
		if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_POSIX_PATHS) {
			int i;
			for (i = 0; i < dfsplen; i++) {
				if (full_path[i] == '\\')
					full_path[i] = '/';
			}
		}
	}
	return full_path;
}

This category addresses vulnerabilities caused by flawed access control mechanisms, where incorrect permission settings allow unauthorized users to access restricted resources.