From patchwork Thu Mar 8 17:20:31 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. Silva" X-Patchwork-Id: 10268549 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id CFE48602BD for ; Thu, 8 Mar 2018 17:21:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C1CFD29AD8 for ; Thu, 8 Mar 2018 17:21:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C022829B08; Thu, 8 Mar 2018 17:21:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id 4A5BC29AD8 for ; Thu, 8 Mar 2018 17:20:50 +0000 (UTC) Received: (qmail 8027 invoked by uid 550); 8 Mar 2018 17:20:46 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 7968 invoked from network); 8 Mar 2018 17:20:44 -0000 Date: Thu, 8 Mar 2018 11:20:31 -0600 From: "Gustavo A. R. Silva" To: Sangbeom Kim , Krzysztof Kozlowski , Bartlomiej Zolnierkiewicz , Alessandro Zummo , Alexandre Belloni Cc: linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-rtc@vger.kernel.org, kernel-hardening@lists.openwall.com, Kees Cook , "Gustavo A. R. Silva" Subject: [PATCH] rtc: s5m: Remove VLA usage Message-ID: <20180308172031.GA14541@embeddedgus> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - lists.openwall.com X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 189.175.117.58 X-Source-L: No X-Exim-ID: 1etzDU-001sYn-4f X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedgus) [189.175.117.58]:58486 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 16 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes X-Virus-Scanned: ClamAV using ClamSMTP In preparation to enabling -Wvla, remove VLAs and replace them with fixed-length arrays instead. From a security viewpoint, the use of Variable Length Arrays can be a vector for stack overflow attacks. Also, in general, as the code evolves it is easy to lose track of how big a VLA can get. Thus, we can end up having segfaults that are hard to debug. Also, fixed as part of the directive to remove all VLAs from the kernel: https://lkml.org/lkml/2018/3/7/621 Signed-off-by: Gustavo A. R. Silva --- drivers/rtc/rtc-s5m.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/rtc/rtc-s5m.c b/drivers/rtc/rtc-s5m.c index 6deae10..2b5f4f7 100644 --- a/drivers/rtc/rtc-s5m.c +++ b/drivers/rtc/rtc-s5m.c @@ -38,6 +38,9 @@ */ #define UDR_READ_RETRY_CNT 5 +/* Maximum number of registers for setting time/alarm0/alarm1 */ +#define MAX_NUM_TIME_REGS 8 + /* * Registers used by the driver which are different between chipsets. * @@ -367,7 +370,7 @@ static void s5m8763_tm_to_data(struct rtc_time *tm, u8 *data) static int s5m_rtc_read_time(struct device *dev, struct rtc_time *tm) { struct s5m_rtc_info *info = dev_get_drvdata(dev); - u8 data[info->regs->regs_count]; + u8 data[MAX_NUM_TIME_REGS]; int ret; if (info->regs->read_time_udr_mask) { @@ -413,7 +416,7 @@ static int s5m_rtc_read_time(struct device *dev, struct rtc_time *tm) static int s5m_rtc_set_time(struct device *dev, struct rtc_time *tm) { struct s5m_rtc_info *info = dev_get_drvdata(dev); - u8 data[info->regs->regs_count]; + u8 data[MAX_NUM_TIME_REGS]; int ret = 0; switch (info->device_type) { @@ -450,7 +453,7 @@ static int s5m_rtc_set_time(struct device *dev, struct rtc_time *tm) static int s5m_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) { struct s5m_rtc_info *info = dev_get_drvdata(dev); - u8 data[info->regs->regs_count]; + u8 data[MAX_NUM_TIME_REGS]; unsigned int val; int ret, i; @@ -500,7 +503,7 @@ static int s5m_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm) static int s5m_rtc_stop_alarm(struct s5m_rtc_info *info) { - u8 data[info->regs->regs_count]; + u8 data[MAX_NUM_TIME_REGS]; int ret, i; struct rtc_time tm; @@ -545,7 +548,7 @@ static int s5m_rtc_stop_alarm(struct s5m_rtc_info *info) static int s5m_rtc_start_alarm(struct s5m_rtc_info *info) { int ret; - u8 data[info->regs->regs_count]; + u8 data[MAX_NUM_TIME_REGS]; u8 alarm0_conf; struct rtc_time tm; @@ -598,7 +601,7 @@ static int s5m_rtc_start_alarm(struct s5m_rtc_info *info) static int s5m_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alrm) { struct s5m_rtc_info *info = dev_get_drvdata(dev); - u8 data[info->regs->regs_count]; + u8 data[MAX_NUM_TIME_REGS]; int ret; switch (info->device_type) {