From patchwork Tue Nov 5 10:01:27 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: 3141101 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 E3E3F9F407 for ; Tue, 5 Nov 2013 13:04:11 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 40EF320580 for ; Tue, 5 Nov 2013 13:04:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E66542061E for ; Tue, 5 Nov 2013 13:04:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754849Ab3KENDz (ORCPT ); Tue, 5 Nov 2013 08:03:55 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:43306 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754816Ab3KENDv (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 1VdgIR-0007gY-0C; 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-0007zy-Bl; 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 14/29] [media] stb0899_drv: Don't use dynamic static allocation Date: Tue, 5 Nov 2013 08:01:27 -0200 Message-Id: <1383645702-30636-15-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/stb0899_drv.c:540:1: warning: 'stb0899_write_regs' 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/stb0899_drv.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/media/dvb-frontends/stb0899_drv.c b/drivers/media/dvb-frontends/stb0899_drv.c index 3dd5714eadba..07cd5ea7a038 100644 --- a/drivers/media/dvb-frontends/stb0899_drv.c +++ b/drivers/media/dvb-frontends/stb0899_drv.c @@ -32,6 +32,9 @@ #include "stb0899_priv.h" #include "stb0899_reg.h" +/* Max transfer size done by I2C transfer functions */ +#define MAX_XFER_SIZE 64 + static unsigned int verbose = 0;//1; module_param(verbose, int, 0644); @@ -499,7 +502,7 @@ err: int stb0899_write_regs(struct stb0899_state *state, unsigned int reg, u8 *data, u32 count) { int ret; - u8 buf[2 + count]; + u8 buf[MAX_XFER_SIZE]; struct i2c_msg i2c_msg = { .addr = state->config->demod_address, .flags = 0, @@ -507,6 +510,13 @@ int stb0899_write_regs(struct stb0899_state *state, unsigned int reg, u8 *data, .len = 2 + count }; + if (2 + count > sizeof(buf)) { + printk(KERN_WARNING + "%s: i2c wr reg=%04x: len=%d is too big!\n", + KBUILD_MODNAME, reg, count); + return -EINVAL; + } + buf[0] = reg >> 8; buf[1] = reg & 0xff; memcpy(&buf[2], data, count);