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Subject[PATCH 09/10] comedi: do_cmd_ioctl(): lift copyin/copyout into the caller
Date
From: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
drivers/staging/comedi/comedi_fops.c | 48 ++++++++++++++++++------------------
1 file changed, 24 insertions(+), 24 deletions(-)

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index a40a865ed45c..f5ecfbfcdaf5 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -1741,9 +1741,8 @@ static int __comedi_get_user_chanlist(struct comedi_device *dev,
* possibly modified comedi_cmd structure (when -EAGAIN returned)
*/
static int do_cmd_ioctl(struct comedi_device *dev,
- struct comedi_cmd __user *arg, void *file)
+ struct comedi_cmd *cmd, bool *copy, void *file)
{
- struct comedi_cmd cmd;
struct comedi_subdevice *s;
struct comedi_async *async;
unsigned int __user *user_chanlist;
@@ -1751,20 +1750,15 @@ static int do_cmd_ioctl(struct comedi_device *dev,

lockdep_assert_held(&dev->mutex);

- if (copy_from_user(&cmd, arg, sizeof(cmd))) {
- dev_dbg(dev->class_dev, "bad cmd address\n");
- return -EFAULT;
- }
-
- /* get the user's cmd and do some simple validation */
- ret = __comedi_get_user_cmd(dev, &cmd);
+ /* do some simple cmd validation */
+ ret = __comedi_get_user_cmd(dev, cmd);
if (ret)
return ret;

/* save user's chanlist pointer so it can be restored later */
- user_chanlist = (unsigned int __user *)cmd.chanlist;
+ user_chanlist = (unsigned int __user *)cmd->chanlist;

- s = &dev->subdevices[cmd.subdev];
+ s = &dev->subdevices[cmd->subdev];
async = s->async;

/* are we locked? (ioctl lock) */
@@ -1780,13 +1774,13 @@ static int do_cmd_ioctl(struct comedi_device *dev,
}

/* make sure channel/gain list isn't too short */
- if (cmd.chanlist_len < 1) {
+ if (cmd->chanlist_len < 1) {
dev_dbg(dev->class_dev, "channel/gain list too short %u < 1\n",
- cmd.chanlist_len);
+ cmd->chanlist_len);
return -EINVAL;
}

- async->cmd = cmd;
+ async->cmd = *cmd;
async->cmd.data = NULL;

/* load channel/gain list */
@@ -1798,15 +1792,11 @@ static int do_cmd_ioctl(struct comedi_device *dev,

if (async->cmd.flags & CMDF_BOGUS || ret) {
dev_dbg(dev->class_dev, "test returned %d\n", ret);
- cmd = async->cmd;
+ *cmd = async->cmd;
/* restore chanlist pointer before copying back */
- cmd.chanlist = (unsigned int __force *)user_chanlist;
- cmd.data = NULL;
- if (copy_to_user(arg, &cmd, sizeof(cmd))) {
- dev_dbg(dev->class_dev, "fault writing cmd\n");
- ret = -EFAULT;
- goto cleanup;
- }
+ cmd->chanlist = (unsigned int __force *)user_chanlist;
+ cmd->data = NULL;
+ *copy = true;
ret = -EAGAIN;
goto cleanup;
}
@@ -2207,9 +2197,19 @@ static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd,
case COMEDI_CANCEL:
rc = do_cancel_ioctl(dev, arg, file);
break;
- case COMEDI_CMD:
- rc = do_cmd_ioctl(dev, (struct comedi_cmd __user *)arg, file);
+ case COMEDI_CMD: {
+ struct comedi_cmd cmd;
+ bool copy = false;
+
+ if (copy_from_user(&cmd, (void __user *)arg, sizeof(cmd))) {
+ rc = -EFAULT;
+ break;
+ }
+ rc = do_cmd_ioctl(dev, &cmd, &copy, file);
+ if (copy && copy_to_user((void __user *)arg, &cmd, sizeof(cmd)))
+ rc = -EFAULT;
break;
+ }
case COMEDI_CMDTEST: {
struct comedi_cmd cmd;
bool copy = false;
--
2.11.0
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