[PATCH 3.10 145/173] media: cxusb: Dont use dynamic static allocation

Greg Kroah-Hartman
2013-12-02T20:37:47Z

From: Mauro Carvalho Chehab <m.chehab@samsung.com>

commit 64f7ef8afbf89f3c72c4d2472e4914ca198c0668 upstream.

Dynamic static allocation is evil, as Kernel stack is too low, and
compilation complains about it on some archs:
drivers/media/usb/dvb-usb/cxusb.c:209:1: warning: 'cxusb_i2c_xfer' uses dynamic stack allocation [enabled by default]
drivers/media/usb/dvb-usb/cxusb.c:69:1: warning: 'cxusb_ctrl_msg' uses dynamic stack allocation [enabled by default]
Instead, let's enforce a limit for the buffer to be the max size of
a control URB payload data (64 bytes).

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Reviewed-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/media/usb/dvb-usb/cxusb.c | 41 ++++++++++++++++++++++++++++++++++----
1 file changed, 37 insertions(+), 4 deletions(-)

--- a/drivers/media/usb/dvb-usb/cxusb.c
+++ b/drivers/media/usb/dvb-usb/cxusb.c
@@ -43,6 +43,9 @@
#include "lgs8gxx.h"
#include "atbm8830.h"

+/* Max transfer size done by I2C transfer functions */
+#define MAX_XFER_SIZE 64
+
/* debug */
static int dvb_usb_cxusb_debug;
module_param_named(debug, dvb_usb_cxusb_debug, int, 0644);
@@ -57,7 +60,14 @@ static int cxusb_ctrl_msg(struct dvb_usb
u8 cmd, u8 *wbuf, int wlen, u8 *rbuf, int rlen)
{
int wo = (rbuf == NULL || rlen == 0); /* write-only */
- u8 sndbuf[1+wlen];
+ u8 sndbuf[MAX_XFER_SIZE];
+
+ if (1 + wlen > sizeof(sndbuf)) {
+ warn("i2c wr: len=%d is too big!\n",
+ wlen);
+ return -EOPNOTSUPP;
+ }
+
memset(sndbuf, 0, 1+wlen);

sndbuf[0] = cmd;
@@ -158,7 +168,13 @@ static int cxusb_i2c_xfer(struct i2c_ada

if (msg[i].flags & I2C_M_RD) {
/* read only */
- u8 obuf[3], ibuf[1+msg[i].len];
+ u8 obuf[3], ibuf[MAX_XFER_SIZE];
+
+ if (1 + msg[i].len > sizeof(ibuf)) {
+ warn("i2c rd: len=%d is too big!\n",
+ msg[i].len);
+ return -EOPNOTSUPP;
+ }
obuf[0] = 0;
obuf[1] = msg[i].len;
obuf[2] = msg[i].addr;
@@ -172,7 +188,18 @@ static int cxusb_i2c_xfer(struct i2c_ada
} else if (i+1 < num && (msg[i+1].flags & I2C_M_RD) &&
msg[i].addr == msg[i+1].addr) {
/* write to then read from same address */
- u8 obuf[3+msg[i].len], ibuf[1+msg[i+1].len];
+ u8 obuf[MAX_XFER_SIZE], ibuf[MAX_XFER_SIZE];
+
+ if (3 + msg[i].len > sizeof(obuf)) {
+ warn("i2c wr: len=%d is too big!\n",
+ msg[i].len);
+ return -EOPNOTSUPP;
+ }
+ if (1 + msg[i + 1].len > sizeof(ibuf)) {
+ warn("i2c rd: len=%d is too big!\n",
+ msg[i + 1].len);
+ return -EOPNOTSUPP;
+ }
obuf[0] = msg[i].len;
obuf[1] = msg[i+1].len;
obuf[2] = msg[i].addr;
@@ -191,7 +218,13 @@ static int cxusb_i2c_xfer(struct i2c_ada
i++;
} else {
/* write only */
- u8 obuf[2+msg[i].len], ibuf;
+ u8 obuf[MAX_XFER_SIZE], ibuf;
+
+ if (2 + msg[i].len > sizeof(obuf)) {
+ warn("i2c wr: len=%d is too big!\n",
+ msg[i].len);
+ return -EOPNOTSUPP;
+ }
obuf[0] = msg[i].addr;
obuf[1] = msg[i].len;
memcpy(&obuf[2], msg[i].buf, msg[i].len);