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

[Tariq Toukan]

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

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

From: Eugenia Emantayev <euge...@mellanox.com>

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

(y)

Signed-off-by: Eugenia Emantayev <euge...@mellanox.com>
Signed-off-by: Tariq Toukan <tar...@mellanox.com>
---
  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.

+       /* 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);
  }