From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELvk6g349pOgRBaTb3xxiVNjFADquj1yf1ioHR5FiyiD/gLX7/ZEWx+i/1pynKc7/fKMtTjT ARC-Seal: i=1; a=rsa-sha256; t=1520532919; cv=none; d=google.com; s=arc-20160816; b=w0Jg6ltYZMXno3TsDAkoThCM2DW3Q1CLuhemO7qwsJRaAtXlWDHCrTAtDUgWJpqauw 0pORdEsPdEPgSXvf6epCMSiBwQ8Wb1OrjPoq3GUdYs6U2FZyZphgd+JgwF2eGCZr+hrL qkd05lNsF4+5dXAFP5kzGryQx8Kwqmn1lM9db4LY7EoW7EYXLYGQWkzgyhCCJzyslwst aDp+/mD1KqGjZ2nEwfp7ErfZmBycuEXj+d7WHZoXGu95uTMOUe5bk0bqqEB5ResxYfrw vlL/iR/LLM7ogG8uj4ziD8iQd7ybnzWg2SA2v2U7xwslu1NLykuzX7ViBt0ofuYMbWlC p3fQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:content-language:in-reply-to:mime-version :user-agent:date:message-id:from:references:cc:to:subject :delivered-to:delivered-to:list-id:list-subscribe:list-unsubscribe :list-help:list-post:precedence:mailing-list :arc-authentication-results; bh=jf7fu/X3+KarsXW7XCwwpa3qEVfgQCALXH8+nDJVNQQ=; b=X29stsQBctDXOD5+xaHvK786mw/kWfMaQ75b6XTjzYQyW/p6q+1n3FLpKjx3/OIM0y 9rQtl/ghB5kiDRLhELkyBBR5D4lpRP/53tuJWgMZHMRcmRiJnKDfIosfWVPO6CQVARLF 7+2uI6q7liQS+PDLBOC1Fe1quVLc57BIX6j4Hh/IF/v2ZjT92EApyV/jqHy8LobN80jx wIVdTyi+zSAZVPabCVvqDr3EEYTtlx4Df8JpkNTm5oX7JimY1emMaszbnK+DpCnkAdwU +vQbIFzPp21sCoB26QpSrlYGTbv65Y7DG8GJt8o+7AzR99X2L4YbMmb1z1L5vlQRYp5t on0Q== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of kernel-hardening-return-12247-gregkh=linuxfoundation.org@lists.openwall.com designates 195.42.179.200 as permitted sender) smtp.mailfrom=kernel-hardening-return-12247-gregkh=linuxfoundation.org@lists.openwall.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of kernel-hardening-return-12247-gregkh=linuxfoundation.org@lists.openwall.com designates 195.42.179.200 as permitted sender) smtp.mailfrom=kernel-hardening-return-12247-gregkh=linuxfoundation.org@lists.openwall.com Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm List-Post: List-Help: List-Unsubscribe: List-Subscribe: Subject: Re: [PATCH] rtc: s5m: Remove VLA usage To: Kees Cook , "Gustavo A. R. Silva" Cc: Sangbeom Kim , Krzysztof Kozlowski , Bartlomiej Zolnierkiewicz , Alessandro Zummo , Alexandre Belloni , LKML , linux-samsung-soc@vger.kernel.org, linux-rtc@vger.kernel.org, Kernel Hardening References: <20180308172031.GA14541@embeddedgus> From: "Gustavo A. R. Silva" Message-ID: <23757731-bfa5-cb4c-ddc0-04103f9a72e0@embeddedor.com> Date: Thu, 8 Mar 2018 12:03:29 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit 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: 1etzt6-002cm8-3c X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: ([192.168.1.66]) [189.175.117.58]:53716 X-Source-Auth: garsilva@embeddedor.com X-Email-Count: 10 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594390903982064564?= X-GMAIL-MSGID: =?utf-8?q?1594394327371844576?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 03/08/2018 11:58 AM, Kees Cook wrote: > On Thu, Mar 8, 2018 at 9:20 AM, Gustavo A. R. Silva > wrote: >> 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 > > I would adjust the various const struct s5m_rtc_reg_config's > .regs_count to be represented by this new define, so the stack and the > structures stay in sync. Something like: > > static const struct s5m_rtc_reg_config s2mps13_rtc_regs = { > .regs_count = MAX_NUM_TIME_REGS - 1, > > ? > Yep. I thought about that and decided to wait for some feedback first. But yeah, I think is that'd be a good change. -- Gustavo > -Kees > >> + >> /* >> * 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) { >> -- >> 2.7.4 >> > > >