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Message-ID: <20180308172031.GA14541@embeddedgus> Date: Thu, 8 Mar 2018 11:20:31 -0600 From: "Gustavo A. R. Silva" <gustavo@...eddedor.com> To: Sangbeom Kim <sbkim73@...sung.com>, Krzysztof Kozlowski <krzk@...nel.org>, Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>, Alessandro Zummo <a.zummo@...ertech.it>, Alexandre Belloni <alexandre.belloni@...tlin.com> Cc: linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org, linux-rtc@...r.kernel.org, kernel-hardening@...ts.openwall.com, Kees Cook <keescook@...omium.org>, "Gustavo A. R. Silva" <garsilva@...eddedor.com> Subject: [PATCH] rtc: s5m: Remove VLA usage 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 <gustavo@...eddedor.com> --- 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) { -- 2.7.4
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