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Subject[PATCH 08/10] comedi: do_cmdtest_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 | 45 ++++++++++++++++++------------------
1 file changed, 22 insertions(+), 23 deletions(-)

diff --git a/drivers/staging/comedi/comedi_fops.c b/drivers/staging/comedi/comedi_fops.c
index e85a143057a1..a40a865ed45c 100644
--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -1856,49 +1856,39 @@ static int do_cmd_ioctl(struct comedi_device *dev,
* possibly modified comedi_cmd structure
*/
static int do_cmdtest_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;
unsigned int __user *user_chanlist;
int ret;

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];

/* user_chanlist can be NULL for COMEDI_CMDTEST ioctl */
if (user_chanlist) {
/* load channel/gain list */
- ret = __comedi_get_user_chanlist(dev, s, user_chanlist, &cmd);
+ ret = __comedi_get_user_chanlist(dev, s, user_chanlist, cmd);
if (ret)
return ret;
}

- ret = s->do_cmdtest(dev, s, &cmd);
+ ret = s->do_cmdtest(dev, s, cmd);

- kfree(cmd.chanlist); /* free kernel copy of user chanlist */
+ kfree(cmd->chanlist); /* free kernel copy of user chanlist */

/* restore chanlist pointer before copying back */
- cmd.chanlist = (unsigned int __force *)user_chanlist;
-
- if (copy_to_user(arg, &cmd, sizeof(cmd))) {
- dev_dbg(dev->class_dev, "bad cmd address\n");
- ret = -EFAULT;
- }
+ cmd->chanlist = (unsigned int __force *)user_chanlist;
+ *copy = true;

return ret;
}
@@ -2220,10 +2210,19 @@ static long comedi_unlocked_ioctl(struct file *file, unsigned int cmd,
case COMEDI_CMD:
rc = do_cmd_ioctl(dev, (struct comedi_cmd __user *)arg, file);
break;
- case COMEDI_CMDTEST:
- rc = do_cmdtest_ioctl(dev, (struct comedi_cmd __user *)arg,
- file);
+ case COMEDI_CMDTEST: {
+ struct comedi_cmd cmd;
+ bool copy = false;
+
+ if (copy_from_user(&cmd, (void __user *)arg, sizeof(cmd))) {
+ rc = -EFAULT;
+ break;
+ }
+ rc = do_cmdtest_ioctl(dev, &cmd, &copy, file);
+ if (copy && copy_to_user((void __user *)arg, &cmd, sizeof(cmd)))
+ rc = -EFAULT;
break;
+ }
case COMEDI_INSNLIST: {
struct comedi_insnlist insnlist;
struct comedi_insn *insns = NULL;
--
2.11.0
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