[PATCH] NFS: Ensure ACL xdr code doesn't overflow.

Signed-off-by: Trond Myklebust <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/nfs_common/nfsacl.c

···
 	if (xdr_decode_word(buf, base, &entries) ||
 	    entries > NFS_ACL_MAX_ENTRIES)
 		return -EINVAL;
+	nfsacl_desc.desc.array_maxlen = entries;
 	err = xdr_decode_array2(buf, base + 4, &nfsacl_desc.desc);
 	if (err)
 		return err;

include/linux/sunrpc/xdr.h

···
 struct xdr_array2_desc {
 	unsigned int elem_size;
 	unsigned int array_len;
+	unsigned int array_maxlen;
 	xdr_xcode_elem_t xcode;
 };
 

net/sunrpc/xdr.c

···
 			return -EINVAL;
 	} else {
 		if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
+		    desc->array_len > desc->array_maxlen ||
 		    (unsigned long) base + 4 + desc->array_len *
 				    desc->elem_size > buf->len)
 			return -EINVAL;