rtc: remove VLA usage (fed9b186) · Commits · 戴 / test

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>

drivers/rtc/rtc-bq32k.c

+5 −1

Original line number	Diff line number	Diff line
		@@ -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);

drivers/rtc/rtc-mcp795.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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;

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