From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] yam: fix a missing-check bug Date: Fri, 05 Oct 2018 11:55:21 -0700 (PDT) Message-ID: <20181005.115521.804633180942667200.davem@davemloft.net> References: <1538755176-22355-1-git-send-email-wang6495@umn.edu> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: kjlu@umn.edu, jpr@f6fbb.org, linux-hams@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: wang6495@umn.edu Return-path: In-Reply-To: <1538755176-22355-1-git-send-email-wang6495@umn.edu> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Wenwen Wang Date: Fri, 5 Oct 2018 10:59:36 -0500 > In yam_ioctl(), the concrete ioctl command is firstly copied from the > user-space buffer 'ifr->ifr_data' to 'ioctl_cmd' and checked through the > following switch statement. If the command is not as expected, an error > code EINVAL is returned. In the following execution the buffer > 'ifr->ifr_data' is copied again in the cases of the switch statement to > specific data structures according to what kind of ioctl command is > requested. However, after the second copy, no re-check is enforced on the > newly-copied command. Given that the buffer 'ifr->ifr_data' is in the user > space, a malicious user can race to change the command between the two > copies. This way, the attacker can inject inconsistent data and cause > undefined behavior. > > This patch adds a re-check in each case of the switch statement if there is > a second copy in that case, to re-check whether the command obtained in the > second copy is the same as the one in the first copy. If not, an error code > EINVAL will be returned. > > Signed-off-by: Wenwen Wang Applied, thanks.