From patchwork Fri Dec 6 12:57:39 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 297946 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id 445BB2C0090 for ; Sat, 7 Dec 2013 00:13:33 +1100 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1VovDi-0007K1-Um; Fri, 06 Dec 2013 13:13:26 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1Vov3u-0000sB-1d for kernel-team@lists.ubuntu.com; Fri, 06 Dec 2013 13:03:18 +0000 Received: from bl20-223-32.dsl.telepac.pt ([2.81.223.32] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1Vov3t-0007oY-Pt; Fri, 06 Dec 2013 13:03:18 +0000 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 3.11 170/272] [media] cimax2: Don't use dynamic static allocation Date: Fri, 6 Dec 2013 12:57:39 +0000 Message-Id: <1386334761-25517-171-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1386334761-25517-1-git-send-email-luis.henriques@canonical.com> References: <1386334761-25517-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.11 Cc: Mauro Carvalho Chehab X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.11.10.1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Mauro Carvalho Chehab commit 278ba83a3a1932805be726bdd7dfb3156286d33a upstream. Dynamic static allocation is evil, as Kernel stack is too low, and compilation complains about it on some archs: drivers/media/pci/cx23885/cimax2.c:149:1: warning: 'netup_write_i2c' 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 Reviewed-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Luis Henriques --- drivers/media/pci/cx23885/cimax2.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/media/pci/cx23885/cimax2.c b/drivers/media/pci/cx23885/cimax2.c index 7344849..16fa7ea 100644 --- a/drivers/media/pci/cx23885/cimax2.c +++ b/drivers/media/pci/cx23885/cimax2.c @@ -26,6 +26,10 @@ #include "cx23885.h" #include "cimax2.h" #include "dvb_ca_en50221.h" + +/* Max transfer size done by I2C transfer functions */ +#define MAX_XFER_SIZE 64 + /**** Bit definitions for MC417_RWD and MC417_OEN registers *** bits 31-16 +-----------+ @@ -125,7 +129,7 @@ static int netup_write_i2c(struct i2c_adapter *i2c_adap, u8 addr, u8 reg, u8 *buf, int len) { int ret; - u8 buffer[len + 1]; + u8 buffer[MAX_XFER_SIZE]; struct i2c_msg msg = { .addr = addr, @@ -134,6 +138,13 @@ static int netup_write_i2c(struct i2c_adapter *i2c_adap, u8 addr, u8 reg, .len = len + 1 }; + if (1 + len > sizeof(buffer)) { + printk(KERN_WARNING + "%s: i2c wr reg=%04x: len=%d is too big!\n", + KBUILD_MODNAME, reg, len); + return -EINVAL; + } + buffer[0] = reg; memcpy(&buffer[1], buf, len);