[PATCH net-next] ethtool: prevent endless loop if eeprom size is smaller than announced

[PATCH net-next] ethtool: prevent endless loop if eeprom size is smaller than announced

[Heiner Kallweit]

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>
---
 net/ethtool/ioctl.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
index f2abc3152..999e2a6be 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;
-- 
2.33.0

Re: [PATCH net-next] ethtool: prevent endless loop if eeprom size is smaller than announced

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (refs/heads/master):

On Mon, 13 Sep 2021 21:58:26 +0200 you wrote:
> 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>
> 
> [...]

Here is the summary with links:
  - [net-next] ethtool: prevent endless loop if eeprom size is smaller than announced
    https://git.kernel.org/netdev/net-next/c/b9bbc4c1debc

You are awesome, thank you!
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