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rtc: remove VLA usage 

In preparation to enabling -Wvla, remove VLA and replace it
with a fixed-length array 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 <garsilva@embeddedor.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Gustavo A. R. Silva 2018-03-07 20:27:56 -06:00 committed by Alexandre Belloni
parent 83bbc5ac63
commit fed9b18611
2 changed files with 6 additions and 2 deletions
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6
drivers/rtc/rtc-bq32k.c
View File

@ -36,6 +36,10 @@
#define BQ32K_CFG2 0x09 /* Trickle charger control */
#define BQ32K_TCFE BIT(6) /* Trickle charge FET bypass */
#define MAX_LEN 10 /* Maximum number of consecutive
* register for this particular RTC.
*/
struct bq32k_regs {
uint8_t seconds;
uint8_t minutes;
@ -74,7 +78,7 @@ static int bq32k_read(struct device *dev, void *data, uint8_t off, uint8_t len)
static int bq32k_write(struct device *dev, void *data, uint8_t off, uint8_t len)
{
struct i2c_client *client = to_i2c_client(dev);
uint8_t buffer[len + 1];
uint8_t buffer[MAX_LEN + 1];
buffer[0] = off;
memcpy(&buffer[1], data, len);

2
drivers/rtc/rtc-mcp795.c
View File

@ -82,7 +82,7 @@ static int mcp795_rtcc_write(struct device *dev, u8 addr, u8 *data, u8 count)
{
struct spi_device *spi = to_spi_device(dev);
int ret;
u8 tx[2 + count];
u8 tx[257];
tx[0] = MCP795_WRITE;
tx[1] = addr;