[dpdk-dev] [PATCH v4 6/8] kni: return -EFAULT if copy_from_user fails

[Stephen Hemminger <stephen@networkplumber.org>]

From: Stephen Hemminger <sthemmin@microsoft.com>

The correct thing to return if user gives a bad data
is to return -EFAULT. Logging is also discouraged because
it could be used as a DoS attack.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 kernel/linux/kni/kni_misc.c | 16 +++++-----------
 1 file changed, 5 insertions(+), 11 deletions(-)

diff --git a/kernel/linux/kni/kni_misc.c b/kernel/linux/kni/kni_misc.c
index b59cf24c2184..be45f823408f 100644
--- a/kernel/linux/kni/kni_misc.c
+++ b/kernel/linux/kni/kni_misc.c
@@ -301,11 +301,8 @@ kni_ioctl_create(struct net *net, uint32_t ioctl_num,
 		return -EINVAL;
 
 	/* Copy kni info from user space */
-	ret = copy_from_user(&dev_info, (void *)ioctl_param, sizeof(dev_info));
-	if (ret) {
-		pr_err("copy_from_user in kni_ioctl_create");
-		return -EIO;
-	}
+	if (copy_from_user(&dev_info, (void *)ioctl_param, sizeof(dev_info)))
+		return -EFAULT;
 
 	/* Check if name is zero-ended */
 	if (strnlen(dev_info.name, sizeof(dev_info.name)) == sizeof(dev_info.name)) {
@@ -427,15 +424,12 @@ kni_ioctl_release(struct net *net, uint32_t ioctl_num,
 	if (_IOC_SIZE(ioctl_num) > sizeof(dev_info))
 		return -EINVAL;
 
-	ret = copy_from_user(&dev_info, (void *)ioctl_param, sizeof(dev_info));
-	if (ret) {
-		pr_err("copy_from_user in kni_ioctl_release");
-		return -EIO;
-	}
+	if (copy_from_user(&dev_info, (void *)ioctl_param, sizeof(dev_info)))
+		return -EFAULT;
 
 	/* Release the network device according to its name */
 	if (strlen(dev_info.name) == 0)
-		return ret;
+		return -EINVAL;
 
 	down_write(&knet->kni_list_lock);
 	list_for_each_entry_safe(dev, n, &knet->kni_list_head, list) {
-- 
2.20.1