The register read function is referencing the dev->ctrlmsg structure outside
of the dev->mutex lock, which can cause corruption of the value if multiple
callers are invoking au0828_readreg() simultaneously.
Use a stack variable to hold the result, and copy the buffer returned by
usb_control_msg() to that variable.
In reality, the whole recv_control_msg() function can probably be collapsed
into au0288_readreg() since it is the only caller.
Also get rid of cmd_msg_dump() since the only case in which the function is
ever called only is ever passed a single byte for the response (and it is
already logged).
Signed-off-by: Devin Heitmueller <dheitmueller@xxxxxxxxxxxxxx>
---
drivers/media/video/au0828/au0828-core.c | 40 +++++++++---------------------
1 files changed, 12 insertions(+), 28 deletions(-)
diff --git a/drivers/media/video/au0828/au0828-core.c b/drivers/media/video/au0828/au0828-core.c
index 65914bc..745a80a 100644
--- a/drivers/media/video/au0828/au0828-core.c
+++ b/drivers/media/video/au0828/au0828-core.c
@@ -56,9 +56,12 @@ static int recv_control_msg(struct au0828_dev *dev, u16 request, u32 value,
u32 au0828_readreg(struct au0828_dev *dev, u16 reg)
{
- recv_control_msg(dev, CMD_REQUEST_IN, 0, reg, dev->ctrlmsg, 1);
- dprintk(8, "%s(0x%04x) = 0x%02x\n", __func__, reg, dev->ctrlmsg[0]);
- return dev->ctrlmsg[0];
+ u8 result = 0;
+
+ recv_control_msg(dev, CMD_REQUEST_IN, 0, reg, &result, 1);
+ dprintk(8, "%s(0x%04x) = 0x%02x\n", __func__, reg, result);
+
+ return result;
}
u32 au0828_writereg(struct au0828_dev *dev, u16 reg, u32 val)
@@ -67,24 +70,6 @@ u32 au0828_writereg(struct au0828_dev *dev, u16 reg, u32 val)
return send_control_msg(dev, CMD_REQUEST_OUT, val, reg);
}
-static void cmd_msg_dump(struct au0828_dev *dev)
-{
- int i;
-
- for (i = 0; i < sizeof(dev->ctrlmsg); i += 16)
- dprintk(2, "%s() %02x %02x %02x %02x %02x %02x %02x %02x "
- "%02x %02x %02x %02x %02x %02x %02x %02x\n",
- __func__,
- dev->ctrlmsg[i+0], dev->ctrlmsg[i+1],
- dev->ctrlmsg[i+2], dev->ctrlmsg[i+3],
- dev->ctrlmsg[i+4], dev->ctrlmsg[i+5],
- dev->ctrlmsg[i+6], dev->ctrlmsg[i+7],
- dev->ctrlmsg[i+8], dev->ctrlmsg[i+9],
- dev->ctrlmsg[i+10], dev->ctrlmsg[i+11],
- dev->ctrlmsg[i+12], dev->ctrlmsg[i+13],
- dev->ctrlmsg[i+14], dev->ctrlmsg[i+15]);
-}
-
static int send_control_msg(struct au0828_dev *dev, u16 request, u32 value,
u16 index)
{
@@ -118,24 +103,23 @@ static int recv_control_msg(struct au0828_dev *dev, u16 request, u32 value,
int status = -ENODEV;
mutex_lock(&dev->mutex);
if (dev->usbdev) {
-
- memset(dev->ctrlmsg, 0, sizeof(dev->ctrlmsg));
-
- /* cp must be memory that has been allocated by kmalloc */
status = usb_control_msg(dev->usbdev,
usb_rcvctrlpipe(dev->usbdev, 0),
request,
USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
value, index,
- cp, size, 1000);
+ dev->ctrlmsg, size, 1000);
status = min(status, 0);
if (status < 0) {
printk(KERN_ERR "%s() Failed receiving control message, error %d.\n",
__func__, status);
- } else
- cmd_msg_dump(dev);
+ }
+
+ /* the host controller requires heap allocated memory, which
+ is why we didn't just pass "cp" into usb_control_msg */
+ memcpy(cp, dev->ctrlmsg, size);
}
mutex_unlock(&dev->mutex);
return status;
--
1.7.1
--
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