From patchwork Tue Nov 5 10:01:28 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mauro Carvalho Chehab X-Patchwork-Id: 3141051 Return-Path: X-Original-To: patchwork-linux-media@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 48EB59F407 for ; Tue, 5 Nov 2013 13:04:01 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 124EB20588 for ; Tue, 5 Nov 2013 13:04:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F21F220580 for ; Tue, 5 Nov 2013 13:03:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754850Ab3KEND4 (ORCPT ); Tue, 5 Nov 2013 08:03:56 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:43299 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754733Ab3KENDv (ORCPT ); Tue, 5 Nov 2013 08:03:51 -0500 Received: from [177.143.133.66] (helo=smtp.w2.samsung.com) by bombadil.infradead.org with esmtpsa (Exim 4.80.1 #2 (Red Hat Linux)) id 1VdgIQ-0007gS-P6; Tue, 05 Nov 2013 13:03:51 +0000 Received: from mchehab by smtp.w2.samsung.com with local (Exim 4.80.1) (envelope-from ) id 1VddSC-000802-C8; Tue, 05 Nov 2013 08:01:44 -0200 From: Mauro Carvalho Chehab Cc: Mauro Carvalho Chehab , Linux Media Mailing List , Mauro Carvalho Chehab Subject: [PATCH v3 15/29] [media] stv0367: Don't use dynamic static allocation Date: Tue, 5 Nov 2013 08:01:28 -0200 Message-Id: <1383645702-30636-16-git-send-email-m.chehab@samsung.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1383645702-30636-1-git-send-email-m.chehab@samsung.com> References: <1383645702-30636-1-git-send-email-m.chehab@samsung.com> To: unlisted-recipients:; (no To-header on input) Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Dynamic static allocation is evil, as Kernel stack is too low, and compilation complains about it on some archs: drivers/media/dvb-frontends/stv0367.c:791:1: warning: 'stv0367_writeregs.constprop.4' uses dynamic stack allocation [enabled by default] Instead, let's enforce a limit for the buffer. Considering that I2C transfers are generally limited, and that devices used on USB has a max data length of 64 bytes for the control URBs. So, it seem safe to use 64 bytes as the hard limit for all those devices. On most cases, the limit is a way lower than that, but this limit is small enough to not affect the Kernel stack, and it is a no brain limit, as using smaller ones would require to either carefully each driver or to take a look on each datasheet. Signed-off-by: Mauro Carvalho Chehab --- drivers/media/dvb-frontends/stv0367.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/media/dvb-frontends/stv0367.c b/drivers/media/dvb-frontends/stv0367.c index 7b6dba3ce55e..458772739423 100644 --- a/drivers/media/dvb-frontends/stv0367.c +++ b/drivers/media/dvb-frontends/stv0367.c @@ -33,6 +33,9 @@ #include "stv0367_regs.h" #include "stv0367_priv.h" +/* Max transfer size done by I2C transfer functions */ +#define MAX_XFER_SIZE 64 + static int stvdebug; module_param_named(debug, stvdebug, int, 0644); @@ -767,7 +770,7 @@ static struct st_register def0367cab[STV0367CAB_NBREGS] = { static int stv0367_writeregs(struct stv0367_state *state, u16 reg, u8 *data, int len) { - u8 buf[len + 2]; + u8 buf[MAX_XFER_SIZE]; struct i2c_msg msg = { .addr = state->config->demod_address, .flags = 0, @@ -776,6 +779,14 @@ int stv0367_writeregs(struct stv0367_state *state, u16 reg, u8 *data, int len) }; int ret; + if (2 + len > sizeof(buf)) { + printk(KERN_WARNING + "%s: i2c wr reg=%04x: len=%d is too big!\n", + KBUILD_MODNAME, reg, len); + return -EINVAL; + } + + buf[0] = MSB(reg); buf[1] = LSB(reg); memcpy(buf + 2, data, len);