ethtool: prevent endless loop if eeprom size is smaller than announced

It shouldn't happen, but can happen that readable eeprom size is smaller
than announced. Then we would be stuck in an endless loop here because
after reaching the actual end reads return eeprom.len = 0. I faced this
issue when making a mistake in driver development. Detect this scenario
and return an error.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index f2abc315288839fdb7a401d1d50e9c8d3e9cf991..999e2a6bed135aa1ded4018ea61539d375d37772 100644 (file)
--- a/net/ethtool/ioctl.c
+++ b/net/ethtool/ioctl.c
@@ -1537,6 +1537,10 @@ static int ethtool_get_any_eeprom(struct net_device *dev, void __user *useraddr,
                ret = getter(dev, &eeprom, data);
                if (ret)
                        break;
+               if (!eeprom.len) {
+                       ret = -EIO;
+                       break;
+               }
                if (copy_to_user(userbuf, data, eeprom.len)) {
                        ret = -EFAULT;
                        break;