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comedi: get rid of compat_alloc_user_space() mess in COMEDI_CMD{,TEST…
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…} compat

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Al Viro committed May 29, 2020
1 parent 0a3ccc7 commit bac42fb
Showing 1 changed file with 66 additions and 115 deletions.
181 changes: 66 additions & 115 deletions drivers/staging/comedi/comedi_fops.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2931,155 +2931,106 @@ static int compat_rangeinfo(struct file *file, unsigned long arg)
}

/* Copy 32-bit cmd structure to native cmd structure. */
static int get_compat_cmd(struct comedi_cmd __user *cmd,
static int get_compat_cmd(struct comedi_cmd *cmd,
struct comedi32_cmd_struct __user *cmd32)
{
int err;
union {
unsigned int uint;
compat_uptr_t uptr;
} temp;

/* Copy cmd structure. */
if (!access_ok(cmd32, sizeof(*cmd32)) ||
!access_ok(cmd, sizeof(*cmd)))
struct comedi32_cmd_struct v32;

if (copy_from_user(&v32, cmd32, sizeof(v32)))
return -EFAULT;

err = 0;
err |= __get_user(temp.uint, &cmd32->subdev);
err |= __put_user(temp.uint, &cmd->subdev);
err |= __get_user(temp.uint, &cmd32->flags);
err |= __put_user(temp.uint, &cmd->flags);
err |= __get_user(temp.uint, &cmd32->start_src);
err |= __put_user(temp.uint, &cmd->start_src);
err |= __get_user(temp.uint, &cmd32->start_arg);
err |= __put_user(temp.uint, &cmd->start_arg);
err |= __get_user(temp.uint, &cmd32->scan_begin_src);
err |= __put_user(temp.uint, &cmd->scan_begin_src);
err |= __get_user(temp.uint, &cmd32->scan_begin_arg);
err |= __put_user(temp.uint, &cmd->scan_begin_arg);
err |= __get_user(temp.uint, &cmd32->convert_src);
err |= __put_user(temp.uint, &cmd->convert_src);
err |= __get_user(temp.uint, &cmd32->convert_arg);
err |= __put_user(temp.uint, &cmd->convert_arg);
err |= __get_user(temp.uint, &cmd32->scan_end_src);
err |= __put_user(temp.uint, &cmd->scan_end_src);
err |= __get_user(temp.uint, &cmd32->scan_end_arg);
err |= __put_user(temp.uint, &cmd->scan_end_arg);
err |= __get_user(temp.uint, &cmd32->stop_src);
err |= __put_user(temp.uint, &cmd->stop_src);
err |= __get_user(temp.uint, &cmd32->stop_arg);
err |= __put_user(temp.uint, &cmd->stop_arg);
err |= __get_user(temp.uptr, &cmd32->chanlist);
err |= __put_user((unsigned int __force *)compat_ptr(temp.uptr),
&cmd->chanlist);
err |= __get_user(temp.uint, &cmd32->chanlist_len);
err |= __put_user(temp.uint, &cmd->chanlist_len);
err |= __get_user(temp.uptr, &cmd32->data);
err |= __put_user(compat_ptr(temp.uptr), &cmd->data);
err |= __get_user(temp.uint, &cmd32->data_len);
err |= __put_user(temp.uint, &cmd->data_len);
return err ? -EFAULT : 0;
cmd->subdev = v32.subdev;
cmd->flags = v32.flags;
cmd->start_src = v32.start_src;
cmd->start_arg = v32.start_arg;
cmd->scan_begin_src = v32.scan_begin_src;
cmd->scan_begin_arg = v32.scan_begin_arg;
cmd->convert_src = v32.convert_src;
cmd->convert_arg = v32.convert_arg;
cmd->scan_end_src = v32.scan_end_src;
cmd->scan_end_arg = v32.scan_end_arg;
cmd->stop_src = v32.stop_src;
cmd->stop_arg = v32.stop_arg;
cmd->chanlist = compat_ptr(v32.chanlist);
cmd->chanlist_len = v32.chanlist_len;
cmd->data = compat_ptr(v32.data);
cmd->data_len = v32.data_len;
return 0;
}

/* Copy native cmd structure to 32-bit cmd structure. */
static int put_compat_cmd(struct comedi32_cmd_struct __user *cmd32,
struct comedi_cmd __user *cmd)
{
int err;
unsigned int temp;

/*
* Copy back most of cmd structure.
*
* Assume the pointer values are already valid.
* (Could use ptr_to_compat() to set them.)
*/
if (!access_ok(cmd, sizeof(*cmd)) ||
!access_ok(cmd32, sizeof(*cmd32)))
return -EFAULT;

err = 0;
err |= __get_user(temp, &cmd->subdev);
err |= __put_user(temp, &cmd32->subdev);
err |= __get_user(temp, &cmd->flags);
err |= __put_user(temp, &cmd32->flags);
err |= __get_user(temp, &cmd->start_src);
err |= __put_user(temp, &cmd32->start_src);
err |= __get_user(temp, &cmd->start_arg);
err |= __put_user(temp, &cmd32->start_arg);
err |= __get_user(temp, &cmd->scan_begin_src);
err |= __put_user(temp, &cmd32->scan_begin_src);
err |= __get_user(temp, &cmd->scan_begin_arg);
err |= __put_user(temp, &cmd32->scan_begin_arg);
err |= __get_user(temp, &cmd->convert_src);
err |= __put_user(temp, &cmd32->convert_src);
err |= __get_user(temp, &cmd->convert_arg);
err |= __put_user(temp, &cmd32->convert_arg);
err |= __get_user(temp, &cmd->scan_end_src);
err |= __put_user(temp, &cmd32->scan_end_src);
err |= __get_user(temp, &cmd->scan_end_arg);
err |= __put_user(temp, &cmd32->scan_end_arg);
err |= __get_user(temp, &cmd->stop_src);
err |= __put_user(temp, &cmd32->stop_src);
err |= __get_user(temp, &cmd->stop_arg);
err |= __put_user(temp, &cmd32->stop_arg);
struct comedi_cmd *cmd)
{
struct comedi32_cmd_struct v32;

memset(&v32, 0, sizeof(v32));
v32.subdev = cmd->subdev;
v32.flags = cmd->flags;
v32.start_src = cmd->start_src;
v32.start_arg = cmd->start_arg;
v32.scan_begin_src = cmd->scan_begin_src;
v32.scan_begin_arg = cmd->scan_begin_arg;
v32.convert_src = cmd->convert_src;
v32.convert_arg = cmd->convert_arg;
v32.scan_end_src = cmd->scan_end_src;
v32.scan_end_arg = cmd->scan_end_arg;
v32.stop_src = cmd->stop_src;
v32.stop_arg = cmd->stop_arg;
/* Assume chanlist pointer is unchanged. */
err |= __get_user(temp, &cmd->chanlist_len);
err |= __put_user(temp, &cmd32->chanlist_len);
/* Assume data pointer is unchanged. */
err |= __get_user(temp, &cmd->data_len);
err |= __put_user(temp, &cmd32->data_len);
return err ? -EFAULT : 0;
v32.chanlist = ptr_to_compat(cmd->chanlist);
v32.chanlist_len = cmd->chanlist_len;
v32.data = ptr_to_compat(cmd->data);
v32.data_len = cmd->data_len;
return copy_to_user(cmd32, &v32, sizeof(v32));
}

/* Handle 32-bit COMEDI_CMD ioctl. */
static int compat_cmd(struct file *file, unsigned long arg)
{
struct comedi_cmd __user *cmd;
struct comedi32_cmd_struct __user *cmd32;
struct comedi_file *cfp = file->private_data;
struct comedi_device *dev = cfp->dev;
struct comedi_cmd cmd;
bool copy = false;
int rc, err;

cmd32 = compat_ptr(arg);
cmd = compat_alloc_user_space(sizeof(*cmd));

rc = get_compat_cmd(cmd, cmd32);
rc = get_compat_cmd(&cmd, compat_ptr(arg));
if (rc)
return rc;

rc = comedi_unlocked_ioctl(file, COMEDI_CMD, (unsigned long)cmd);
if (rc == -EAGAIN) {
mutex_lock(&dev->mutex);
rc = do_cmd_ioctl(dev, &cmd, &copy, file);
mutex_unlock(&dev->mutex);
if (copy) {
/* Special case: copy cmd back to user. */
err = put_compat_cmd(cmd32, cmd);
err = put_compat_cmd(compat_ptr(arg), &cmd);
if (err)
rc = err;
}

return rc;
}

/* Handle 32-bit COMEDI_CMDTEST ioctl. */
static int compat_cmdtest(struct file *file, unsigned long arg)
{
struct comedi_cmd __user *cmd;
struct comedi32_cmd_struct __user *cmd32;
struct comedi_file *cfp = file->private_data;
struct comedi_device *dev = cfp->dev;
struct comedi_cmd cmd;
bool copy = false;
int rc, err;

cmd32 = compat_ptr(arg);
cmd = compat_alloc_user_space(sizeof(*cmd));

rc = get_compat_cmd(cmd, cmd32);
rc = get_compat_cmd(&cmd, compat_ptr(arg));
if (rc)
return rc;

rc = comedi_unlocked_ioctl(file, COMEDI_CMDTEST, (unsigned long)cmd);
if (rc < 0)
return rc;

err = put_compat_cmd(cmd32, cmd);
if (err)
rc = err;

mutex_lock(&dev->mutex);
rc = do_cmdtest_ioctl(dev, &cmd, &copy, file);
mutex_unlock(&dev->mutex);
if (copy) {
err = put_compat_cmd(compat_ptr(arg), &cmd);
if (err)
rc = err;
}
return rc;
}

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