From: Heiner Kallweit <hkallweit1@gmail.com>
Date: Mon, 13 Sep 2021 19:58:26 +0000 (+0200)
Subject: ethtool: prevent endless loop if eeprom size is smaller than announced
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=b9bbc4c1debc837ba56872fb3b2499ba6459ca8b;p=linux.git

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 f2abc31528883..999e2a6bed135 100644
--- 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;