From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753171AbeEGXIq (ORCPT ); Mon, 7 May 2018 19:08:46 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:51028 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752786AbeEGXIo (ORCPT ); Mon, 7 May 2018 19:08:44 -0400 From: Colin King To: Daniel Scheller , Mauro Carvalho Chehab , linux-media@vger.kernel.org Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH][media-next] media: ddbridge: avoid out-of-bounds write on array demod_in_use Date: Tue, 8 May 2018 00:08:42 +0100 Message-Id: <20180507230842.28409-1-colin.king@canonical.com> X-Mailer: git-send-email 2.17.0 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Colin Ian King In function stop there is a check to see if state->demod is a stopped value of 0xff, however, later on, array demod_in_use is indexed with this value causing an out-of-bounds write error. Avoid this by only writing to array demod_in_use if state->demod is not set to the stopped sentinal value for this specific corner case. Also, replace the magic value 0xff with DEMOD_STOPPED to make code more readable. Detected by CoverityScan, CID#1468550 ("Out-of-bounds write") Fixes: daeeb1319e6f ("media: ddbridge: initial support for MCI-based MaxSX8 cards") Signed-off-by: Colin Ian King --- drivers/media/pci/ddbridge/ddbridge-mci.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/media/pci/ddbridge/ddbridge-mci.c b/drivers/media/pci/ddbridge/ddbridge-mci.c index a85ff3e6b919..1f5ed53c8d35 100644 --- a/drivers/media/pci/ddbridge/ddbridge-mci.c +++ b/drivers/media/pci/ddbridge/ddbridge-mci.c @@ -20,6 +20,8 @@ #include "ddbridge-io.h" #include "ddbridge-mci.h" +#define DEMOD_STOPPED (0xff) + static LIST_HEAD(mci_list); static const u32 MCLK = (1550000000 / 12); @@ -193,7 +195,7 @@ static int stop(struct dvb_frontend *fe) u32 input = state->tuner; memset(&cmd, 0, sizeof(cmd)); - if (state->demod != 0xff) { + if (state->demod != DEMOD_STOPPED) { cmd.command = MCI_CMD_STOP; cmd.demod = state->demod; mci_cmd(state, &cmd, NULL); @@ -209,10 +211,11 @@ static int stop(struct dvb_frontend *fe) state->base->tuner_use_count[input]--; if (!state->base->tuner_use_count[input]) mci_set_tuner(fe, input, 0); - state->base->demod_in_use[state->demod] = 0; + if (state->demod != DEMOD_STOPPED) + state->base->demod_in_use[state->demod] = 0; state->base->used_ldpc_bitrate[state->nr] = 0; - state->demod = 0xff; - state->base->assigned_demod[state->nr] = 0xff; + state->demod = DEMOD_STOPPED; + state->base->assigned_demod[state->nr] = DEMOD_STOPPED; state->base->iq_mode = 0; mutex_unlock(&state->base->tuner_lock); state->started = 0; -- 2.17.0