From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from aserp1040.oracle.com ([141.146.126.69]:47061 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759947Ab3DBHxQ (ORCPT ); Tue, 2 Apr 2013 03:53:16 -0400 Date: Tue, 2 Apr 2013 10:51:02 +0300 From: Dan Carpenter To: Mauro Carvalho Chehab Cc: Antti Palosaari , Michael Krufky , Peter Senna Tschudin , linux-media@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: [RFC] [media] dvb-core: check ->msg_len for diseqc_send_master_cmd() Message-ID: <20130402075102.GA11233@longonot.mountain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-media-owner@vger.kernel.org List-ID: I'd like to send this patch except that it "breaks" cx24116_send_diseqc_msg(). The cx24116 driver accepts ->msg_len values up to 24 but it looks like it's just copying 16 bytes past the end of the ->msg[] array so it's already broken. cmd->msg_len is an unsigned char. The comment next to the struct declaration says that valid values are are 3-6. Some of the drivers check that this is true, but most don't and it could cause memory corruption. Some examples of functions which don't check are: ttusbdecfe_dvbs_diseqc_send_master_cmd() cx24123_send_diseqc_msg() ds3000_send_diseqc_msg() etc. Signed-off-by: Dan Carpenter diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c index 57601c0..3d1eee6 100644 --- a/drivers/media/dvb-core/dvb_frontend.c +++ b/drivers/media/dvb-core/dvb_frontend.c @@ -2265,7 +2265,13 @@ static int dvb_frontend_ioctl_legacy(struct file *file, case FE_DISEQC_SEND_MASTER_CMD: if (fe->ops.diseqc_send_master_cmd) { - err = fe->ops.diseqc_send_master_cmd(fe, (struct dvb_diseqc_master_cmd*) parg); + struct dvb_diseqc_master_cmd *cmd = parg; + + if (cmd->msg_len >= 3 && cmd->msg_len <= 6) + err = fe->ops.diseqc_send_master_cmd(fe, cmd); + else + err = -EINVAL; + fepriv->state = FESTATE_DISEQC; fepriv->status = 0; }