From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Carpenter Subject: [patch] rds: fix an integer overflow test in rds_info_getsockopt() Date: Sat, 1 Aug 2015 15:33:26 +0300 Message-ID: <20150801123326.GA5075@mwanda> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "David S. Miller" , rds-devel@oss.oracle.com, netdev@vger.kernel.org, kernel-janitors@vger.kernel.org To: Chien Yen , Andy Grover Return-path: Received: from aserp1040.oracle.com ([141.146.126.69]:23780 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751214AbbHAMdt (ORCPT ); Sat, 1 Aug 2015 08:33:49 -0400 Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-ID: "len" is a signed integer. We check that len is not negative, so it goes from zero to INT_MAX. PAGE_SIZE is unsigned long so the comparison is type promoted to unsigned long. ULONG_MAX - 4095 is a higher than INT_MAX so the condition can never be true. I don't know if this is harmful but it seems safe to limit "len" to INT_MAX - 4095. Fixes: a8c879a7ee98 ('RDS: Info and stats') Signed-off-by: Dan Carpenter diff --git a/net/rds/info.c b/net/rds/info.c index 9a6b4f6..140a44a 100644 --- a/net/rds/info.c +++ b/net/rds/info.c @@ -176,7 +176,7 @@ int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval, /* check for all kinds of wrapping and the like */ start = (unsigned long)optval; - if (len < 0 || len + PAGE_SIZE - 1 < len || start + len < start) { + if (len < 0 || len > INT_MAX - PAGE_SIZE + 1 || start + len < start) { ret = -EINVAL; goto out; }