V4L/DVB: media/az6027: doing dma on the stack

I changed the dma buffers to use allocated memory instead of stack
memory.

The reason for this is documented in Documentation/DMA-API-HOWTO.txt
under the section:  "What memory is DMA'able?"  That document was only
added a couple weeks ago and there are still lots of modules which
haven't been corrected yet.  Btw. Smatch includes a pretty good test to
find places which use stack memory as a dma buffer.  That's how I found
these.  (http://smatch.sf.net).

Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 41 insertions, 9 deletions

diff --git a/drivers/media/dvb/dvb-usb/az6027.c b/drivers/media/dvb/dvb-usb/az6027.c
index 8934788bd83b..baaa301c5768 100644
--- a/drivers/media/dvb/dvb-usb/az6027.c
+++ b/drivers/media/dvb/dvb-usb/az6027.c
@@ -417,11 +417,15 @@ static int az6027_ci_read_attribute_mem(struct dvb_ca_en50221 *ca,
         u16 value;
         u16 index;
         int blen;
-        u8 b[12];
+        u8 *b;
 
         if (slot != 0)
                 return -EINVAL;
 
+        b = kmalloc(12, GFP_KERNEL);
+        if (!b)
+                return -ENOMEM;
+
         mutex_lock(&state->ca_mutex);
 
         req = 0xC1;
@@ -438,6 +442,7 @@ static int az6027_ci_read_attribute_mem(struct dvb_ca_en50221 *ca,
         }
 
         mutex_unlock(&state->ca_mutex);
+        kfree(b);
         return ret;
 }
 
@@ -485,11 +490,15 @@ static int az6027_ci_read_cam_control(struct dvb_ca_en50221 *ca,
         u16 value;
         u16 index;
         int blen;
-        u8 b[12];
+        u8 *b;
 
         if (slot != 0)
                 return -EINVAL;
 
+        b = kmalloc(12, GFP_KERNEL);
+        if (!b)
+                return -ENOMEM;
+
         mutex_lock(&state->ca_mutex);
 
         req = 0xC3;
@@ -510,6 +519,7 @@ static int az6027_ci_read_cam_control(struct dvb_ca_en50221 *ca,
         }
 
         mutex_unlock(&state->ca_mutex);
+        kfree(b);
         return ret;
 }
 
@@ -556,7 +566,11 @@ static int CI_CamReady(struct dvb_ca_en50221 *ca, int slot)
         u16 value;
         u16 index;
         int blen;
-        u8 b[12];
+        u8 *b;
+
+        b = kmalloc(12, GFP_KERNEL);
+        if (!b)
+                return -ENOMEM;
 
         req = 0xC8;
         value = 0;
@@ -570,6 +584,7 @@ static int CI_CamReady(struct dvb_ca_en50221 *ca, int slot)
         } else{
                 ret = b[0];
         }
+        kfree(b);
         return ret;
 }
 
@@ -667,8 +682,11 @@ static int az6027_ci_poll_slot_status(struct dvb_ca_en50221 *ca, int slot, int o
         u16 value;
         u16 index;
         int blen;
-        u8 b[12];
+        u8 *b;
 
+        b = kmalloc(12, GFP_KERNEL);
+        if (!b)
+                return -ENOMEM;
         mutex_lock(&state->ca_mutex);
 
         req = 0xC5;
@@ -692,6 +710,7 @@ static int az6027_ci_poll_slot_status(struct dvb_ca_en50221 *ca, int slot, int o
         }
 
         mutex_unlock(&state->ca_mutex);
+        kfree(b);
         return ret;
 }
 
@@ -943,10 +962,16 @@ static int az6027_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], int n
         u16 value;
         int length;
         u8 req;
-        u8 data[256];
+        u8 *data;
+
+        data = kmalloc(256, GFP_KERNEL);
+        if (!data)
+                return -ENOMEM;
 
-        if (mutex_lock_interruptible(&d->i2c_mutex) < 0)
+        if (mutex_lock_interruptible(&d->i2c_mutex) < 0) {
+                kfree(data);
                 return -EAGAIN;
+        }
 
         if (num > 2)
                 warn("more than 2 i2c messages at a time is not handled yet. TODO.");
@@ -1016,6 +1041,7 @@ static int az6027_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msg[], int n
                 }
         }
         mutex_unlock(&d->i2c_mutex);
+        kfree(data);
 
         return i;
 }
@@ -1036,8 +1062,14 @@ int az6027_identify_state(struct usb_device *udev,
                           struct dvb_usb_device_description **desc,
                           int *cold)
 {
-        u8 b[16];
-        s16 ret = usb_control_msg(udev,
+        u8 *b;
+        s16 ret;
+
+        b = kmalloc(16, GFP_KERNEL);
+        if (!b)
+                return -ENOMEM;
+
+        ret = usb_control_msg(udev,
                                   usb_rcvctrlpipe(udev, 0),
                                   0xb7,
                                   USB_TYPE_VENDOR | USB_DIR_IN,
@@ -1048,7 +1080,7 @@ int az6027_identify_state(struct usb_device *udev,
                                   USB_CTRL_GET_TIMEOUT);
 
         *cold = ret <= 0;
-
+        kfree(b);
         deb_info("cold: %d\n", *cold);
         return 0;
 }