xfs: prevent a WARN_ONCE() in xfs_ioc_attr_list()

The "bufsize" comes from the root user.  If "bufsize" is negative then,
because of type promotion, neither of the validation checks at the start
of the function are able to catch it:

	if (bufsize < sizeof(struct xfs_attrlist) ||
	    bufsize > XFS_XATTR_LIST_MAX)
		return -EINVAL;

This means "bufsize" will trigger (WARN_ON_ONCE(size > INT_MAX)) in
kvmalloc_node().  Fix this by changing the type from int to size_t.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>

Author: Dan Carpenter

fs/xfs/xfs_ioctl.c

@@ -372,7 +372,7 @@ int
 xfs_ioc_attr_list(
 	struct xfs_inode		*dp,
 	void __user			*ubuf,
-	int				bufsize,
+	size_t				bufsize,
 	int				flags,
 	struct xfs_attrlist_cursor __user *ucursor)
 {

fs/xfs/xfs_ioctl.h

@@ -38,8 +38,9 @@ xfs_readlink_by_handle(
 int xfs_ioc_attrmulti_one(struct file *parfilp, struct inode *inode,
 		uint32_t opcode, void __user *uname, void __user *value,
 		uint32_t *len, uint32_t flags);
-int xfs_ioc_attr_list(struct xfs_inode *dp, void __user *ubuf, int bufsize,
-	int flags, struct xfs_attrlist_cursor __user *ucursor);
+int xfs_ioc_attr_list(struct xfs_inode *dp, void __user *ubuf,
+		      size_t bufsize, int flags,
+		      struct xfs_attrlist_cursor __user *ucursor);
 
 extern struct dentry *
 xfs_handle_to_dentry(