[PATCH 5.10 076/145] Staging: comedi: Return -EFAULT if copy_to_user() fails

Greg Kroah-Hartman
2021-01-11T13:17:12Z

From: Dan Carpenter <dan.carpenter@oracle.com>

commit cab36da4bf1a35739b091b73714a39a1bbd02b05 upstream.

Return -EFAULT on error instead of the number of bytes remaining to be
copied.

Fixes: bac42fb21259 ("comedi: get rid of compat_alloc_user_space() mess in COMEDI_CMD{,TEST} compat")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/X8c3pfwFy2jpy4BP@mwanda
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/staging/comedi/comedi_fops.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/staging/comedi/comedi_fops.c
+++ b/drivers/staging/comedi/comedi_fops.c
@@ -2987,7 +2987,9 @@ static int put_compat_cmd(struct comedi3
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));
+ if (copy_to_user(cmd32, &v32, sizeof(v32)))
+ return -EFAULT;
+ return 0;
}

/* Handle 32-bit COMEDI_CMD ioctl. */