media: cxusb: Don't use dynamic static allocation
Mauro Carvalho Chehab [Sat, 2 Nov 2013 10:18:09 +0000 (07:18 -0300)]
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

index 3940bb0..20e345d 100644 (file)
@@ -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_device *d,
                          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_adapter *adap, struct i2c_msg msg[],
 
                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_adapter *adap, struct i2c_msg msg[],
                } 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_adapter *adap, struct i2c_msg msg[],
                        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);