[media] dvb-frontends: Don't use dynamic static allocation

Dynamic static allocation is evil, as Kernel stack is too low, and
compilation complains about it on some archs:
drivers/media/dvb-frontends/bcm3510.c:230:1: warning: 'bcm3510_do_hab_cmd' uses dynamic stack allocation [enabled by default]
drivers/media/dvb-frontends/itd1000.c:69:1: warning: 'itd1000_write_regs.constprop.0' uses dynamic stack allocation [enabled by default]
drivers/media/dvb-frontends/mt312.c:126:1: warning: 'mt312_write' uses dynamic stack allocation [enabled by default]
drivers/media/dvb-frontends/nxt200x.c:111:1: warning: 'nxt200x_writebytes' uses dynamic stack allocation [enabled by default]
drivers/media/dvb-frontends/stb6100.c:216:1: warning: 'stb6100_write_reg_range.constprop.3' uses dynamic stack allocation [enabled by default]
drivers/media/dvb-frontends/stv6110.c:98:1: warning: 'stv6110_write_regs' uses dynamic stack allocation [enabled by default]
drivers/media/dvb-frontends/stv6110x.c:85:1: warning: 'stv6110x_write_regs' uses dynamic stack allocation [enabled by default]
drivers/media/dvb-frontends/tda18271c2dd.c:147:1: warning: 'WriteRegs' uses dynamic stack allocation [enabled by default]
drivers/media/dvb-frontends/zl10039.c:119:1: warning: 'zl10039_write' uses dynamic stack allocation [enabled by default]
Instead, let's enforce a limit for the buffer. Considering that I2C
transfers are generally limited, and that devices used on USB has a
max data length of 64 bytes for the control URBs.
So, it seem safe to use 64 bytes as the hard limit for all those devices.
On most cases, the limit is a way lower than that, but this limit
is small enough to not affect the Kernel stack, and it is a no brain
limit, as using smaller ones would require to either carefully each
driver or to take a look on each datasheet.

Signed-off-by: Mauro Carvalho Chehab <[e-mail]>
Reviewed-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/dvb-frontends/bcm3510.c

···
 #include "bcm3510.h"
 #include "bcm3510_priv.h"
 
+/* Max transfer size done by bcm3510_do_hab_cmd() function */
+#define MAX_XFER_SIZE	128
+
 struct bcm3510_state {
 
 	struct i2c_adapter* i2c;
···
 
 static int bcm3510_do_hab_cmd(struct bcm3510_state *st, u8 cmd, u8 msgid, u8 *obuf, u8 olen, u8 *ibuf, u8 ilen)
 {
-	u8 ob[olen+2],ib[ilen+2];
+	u8 ob[MAX_XFER_SIZE], ib[MAX_XFER_SIZE];
 	int ret = 0;
+
+	if (ilen + 2 > sizeof(ib)) {
+		deb_hab("do_hab_cmd: ilen=%d is too big!\n", ilen);
+		return -EINVAL;
+	}
+
+	if (olen + 2 > sizeof(ob)) {
+		deb_hab("do_hab_cmd: olen=%d is too big!\n", olen);
+		return -EINVAL;
+	}
 
 	ob[0] = cmd;
 	ob[1] = msgid;

drivers/media/dvb-frontends/itd1000.c

···
 #include "itd1000.h"
 #include "itd1000_priv.h"
 
+/* Max transfer size done by I2C transfer functions */
+#define MAX_XFER_SIZE  64
+
 static int debug;
 module_param(debug, int, 0644);
 MODULE_PARM_DESC(debug, "Turn on/off debugging (default:off).");
···
 /* don't write more than one byte with flexcop behind */
 static int itd1000_write_regs(struct itd1000_state *state, u8 reg, u8 v[], u8 len)
 {
-	u8 buf[1+len];
+	u8 buf[MAX_XFER_SIZE];
 	struct i2c_msg msg = {
 		.addr = state->cfg->i2c_address, .flags = 0, .buf = buf, .len = len+1
 	};
+
+	if (1 + len > sizeof(buf)) {
+		printk(KERN_WARNING
+		       "itd1000: i2c wr reg=%04x: len=%d is too big!\n",
+		       reg, len);
+		return -EINVAL;
+	}
+
 	buf[0] = reg;
 	memcpy(&buf[1], v, len);
 

drivers/media/dvb-frontends/mt312.c

···
 #include "mt312_priv.h"
 #include "mt312.h"
 
+/* Max transfer size done by I2C transfer functions */
+#define MAX_XFER_SIZE  64
 
 struct mt312_state {
 	struct i2c_adapter *i2c;
···
 		       const u8 *src, const size_t count)
 {
 	int ret;
-	u8 buf[count + 1];
+	u8 buf[MAX_XFER_SIZE];
 	struct i2c_msg msg;
+
+	if (1 + count > sizeof(buf)) {
+		printk(KERN_WARNING
+		       "mt312: write: len=%zd is too big!\n", count);
+		return -EINVAL;
+	}
 
 	if (debug) {
 		int i;

drivers/media/dvb-frontends/nxt200x.c

···
  */
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+/* Max transfer size done by I2C transfer functions */
+#define MAX_XFER_SIZE  64
+
 #define NXT2002_DEFAULT_FIRMWARE "dvb-fe-nxt2002.fw"
 #define NXT2004_DEFAULT_FIRMWARE "dvb-fe-nxt2004.fw"
 #define CRC_CCIT_MASK 0x1021
···
 static int nxt200x_writebytes (struct nxt200x_state* state, u8 reg,
 			       const u8 *buf, u8 len)
 {
-	u8 buf2 [len+1];
+	u8 buf2[MAX_XFER_SIZE];
 	int err;
 	struct i2c_msg msg = { .addr = state->config->demod_address, .flags = 0, .buf = buf2, .len = len + 1 };
+
+	if (1 + len > sizeof(buf2)) {
+		pr_warn("%s: i2c wr reg=%04x: len=%d is too big!\n",
+			 __func__, reg, len);
+		return -EINVAL;
+	}
 
 	buf2[0] = reg;
 	memcpy(&buf2[1], buf, len);

drivers/media/dvb-frontends/stb6100.c

···
 static unsigned int verbose;
 module_param(verbose, int, 0644);
 
+/* Max transfer size done by I2C transfer functions */
+#define MAX_XFER_SIZE  64
 
 #define FE_ERROR		0
 #define FE_NOTICE		1
···
 static int stb6100_write_reg_range(struct stb6100_state *state, u8 buf[], int start, int len)
 {
 	int rc;
-	u8 cmdbuf[len + 1];
+	u8 cmdbuf[MAX_XFER_SIZE];
 	struct i2c_msg msg = {
 		.addr	= state->config->tuner_address,
 		.flags	= 0,
 		.buf	= cmdbuf,
 		.len	= len + 1
 	};
+
+	if (1 + len > sizeof(buf)) {
+		printk(KERN_WARNING
+		       "%s: i2c wr: len=%d is too big!\n",
+		       KBUILD_MODNAME, len);
+		return -EINVAL;
+	}
 
 	if (unlikely(start < 1 || start + len > STB6100_NUMREGS)) {
 		dprintk(verbose, FE_ERROR, 1, "Invalid register range %d:%d",

drivers/media/dvb-frontends/stv6110.c

···
 
 #include "stv6110.h"
 
+/* Max transfer size done by I2C transfer functions */
+#define MAX_XFER_SIZE  64
+
 static int debug;
 
 struct stv6110_priv {
···
 {
 	struct stv6110_priv *priv = fe->tuner_priv;
 	int rc;
-	u8 cmdbuf[len + 1];
+	u8 cmdbuf[MAX_XFER_SIZE];
 	struct i2c_msg msg = {
 		.addr	= priv->i2c_address,
 		.flags	= 0,
···
 	};
 
 	dprintk("%s\n", __func__);
+
+	if (1 + len > sizeof(cmdbuf)) {
+		printk(KERN_WARNING
+		       "%s: i2c wr: len=%d is too big!\n",
+		       KBUILD_MODNAME, len);
+		return -EINVAL;
+	}
 
 	if (start + len > 8)
 		return -EINVAL;

drivers/media/dvb-frontends/stv6110x.c

···
 #include "stv6110x.h"
 #include "stv6110x_priv.h"
 
+/* Max transfer size done by I2C transfer functions */
+#define MAX_XFER_SIZE  64
+
 static unsigned int verbose;
 module_param(verbose, int, 0644);
 MODULE_PARM_DESC(verbose, "Set Verbosity level");
···
 {
 	int ret;
 	const struct stv6110x_config *config = stv6110x->config;
-	u8 buf[len + 1];
+	u8 buf[MAX_XFER_SIZE];
+
 	struct i2c_msg msg = {
 		.addr = config->addr,
 		.flags = 0,
 		.buf = buf,
 		.len = len + 1
 	};
+
+	if (1 + len > sizeof(buf)) {
+		printk(KERN_WARNING
+		       "%s: i2c wr: len=%d is too big!\n",
+		       KBUILD_MODNAME, len);
+		return -EINVAL;
+	}
 
 	if (start + len > 8)
 		return -EINVAL;

drivers/media/dvb-frontends/tda18271c2dd.c

···
 #include "dvb_frontend.h"
 #include "tda18271c2dd.h"
 
+/* Max transfer size done by I2C transfer functions */
+#define MAX_XFER_SIZE  64
+
 struct SStandardParam {
 	s32   m_IFFrequency;
 	u32   m_BandWidth;
···
 static int WriteRegs(struct tda_state *state,
 		     u8 SubAddr, u8 *Regs, u16 nRegs)
 {
-	u8 data[nRegs+1];
+	u8 data[MAX_XFER_SIZE];
+
+	if (1 + nRegs > sizeof(data)) {
+		printk(KERN_WARNING
+		       "%s: i2c wr: len=%d is too big!\n",
+		       KBUILD_MODNAME, nRegs);
+		return -EINVAL;
+	}
 
 	data[0] = SubAddr;
 	memcpy(data + 1, Regs, nRegs);
-	return i2c_write(state->i2c, state->adr, data, nRegs+1);
+	return i2c_write(state->i2c, state->adr, data, nRegs + 1);
 }
 
 static int WriteReg(struct tda_state *state, u8 SubAddr, u8 Reg)

drivers/media/dvb-frontends/zl10039.c

···
 
 static int debug;
 
+/* Max transfer size done by I2C transfer functions */
+#define MAX_XFER_SIZE  64
+
 #define dprintk(args...) \
 	do { \
 		if (debug) \
···
 			const enum zl10039_reg_addr reg, const u8 *src,
 			const size_t count)
 {
-	u8 buf[count + 1];
+	u8 buf[MAX_XFER_SIZE];
 	struct i2c_msg msg = {
 		.addr = state->i2c_addr,
 		.flags = 0,
 		.buf = buf,
 		.len = count + 1,
 	};
+
+	if (1 + count > sizeof(buf)) {
+		printk(KERN_WARNING
+		       "%s: i2c wr reg=%04x: len=%zd is too big!\n",
+		       KBUILD_MODNAME, reg, count);
+		return -EINVAL;
+	}
 
 	dprintk("%s\n", __func__);
 	/* Write register address and data in one go */