Re: [PATCH net-next 1/3] ethtool: Ensure new ring parameters are within bounds during SRINGPARAM

On 09/01/2018 4:23 AM, Jakub Kicinski wrote:

On Mon,  8 Jan 2018 16:00:24 +0200, Tariq Toukan wrote:

quoted

From: Eugenia Emantayev <redacted>

Add a sanity check to ensure that all requested ring parameters
are within bounds, which should reduce errors in driver implementation.

(y)

quoted

Signed-off-by: Eugenia Emantayev <redacted>
Signed-off-by: Tariq Toukan <redacted>
---
  net/core/ethtool.c | 13 +++++++++++--
  1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 50a79203043b..9ea7cd52fde0 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c

@@ -1704,14 +1704,23 @@ static int ethtool_get_ringparam(struct net_device *dev, void __user *useraddr)
  
  static int ethtool_set_ringparam(struct net_device *dev, void __user *useraddr)
  {
-	struct ethtool_ringparam ringparam;
+	struct ethtool_ringparam ringparam, max = { .cmd = ETHTOOL_GRINGPARAM };
  
-	if (!dev->ethtool_ops->set_ringparam)
+	if (!dev->ethtool_ops->set_ringparam || !dev->ethtool_ops->get_ringparam)
  		return -EOPNOTSUPP;
  
  	if (copy_from_user(&ringparam, useraddr, sizeof(ringparam)))
  		return -EFAULT;
  
+	dev->ethtool_ops->get_ringparam(dev, &max);

Perhaps check the return value here?  It's pretty unlikely but
get_ringparam may fail.

get_ringparam NDO returns void.

quoted

+	/* ensure new ring parameters are within the maximums */
+	if (ringparam.rx_pending > max.rx_max_pending ||
+	    ringparam.rx_mini_pending > max.rx_mini_max_pending ||
+	    ringparam.rx_jumbo_pending > max.rx_jumbo_max_pending ||
+	    ringparam.tx_pending > max.tx_max_pending)
+		return -EINVAL;
+
  	return dev->ethtool_ops->set_ringparam(dev, &ringparam);
  }