On 03/08/2018 11:58 AM, Kees Cook wrote:
On Thu, Mar 8, 2018 at 9:20 AM, Gustavo A. R. Silva
<gustavo@xxxxxxxxxxxxxx> 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 <gustavo@xxxxxxxxxxxxxx>
---
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
