[PATCH v0] net: ethtool: Only set supplied eee ethtool settings

[PATCH v0] net: ethtool: Only set supplied eee ethtool settings

[Rutger van Kruiningen]

Originally all ethtool eee setting updates were attempted even if the
settings were not supplied, causing a null pointer crash.

Add check for each eee setting and only update if it exists.

Signed-off-by: Rutger van Kruiningen <rutger.vankruiningen@alliedtelesis.co.nz>
---
 net/ethtool/eee.c | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/net/ethtool/eee.c b/net/ethtool/eee.c
index bf398973eb8a..1b4831ff9a75 100644
--- a/net/ethtool/eee.c
+++ b/net/ethtool/eee.c
@@ -137,17 +137,26 @@ ethnl_set_eee(struct ethnl_req_info *req_info, struct genl_info *info)
 	if (ret < 0)
 		return ret;
 
-	ret = ethnl_update_bitset(eee.advertised,
-				  __ETHTOOL_LINK_MODE_MASK_NBITS,
-				  tb[ETHTOOL_A_EEE_MODES_OURS],
-				  link_mode_names, info->extack, &mod);
-	if (ret < 0)
-		return ret;
-	ethnl_update_bool(&eee.eee_enabled, tb[ETHTOOL_A_EEE_ENABLED], &mod);
-	ethnl_update_bool(&eee.tx_lpi_enabled, tb[ETHTOOL_A_EEE_TX_LPI_ENABLED],
-			  &mod);
-	ethnl_update_u32(&eee.tx_lpi_timer, tb[ETHTOOL_A_EEE_TX_LPI_TIMER],
-			 &mod);
+	if (tb[ETHTOOL_A_EEE_MODES_OURS]) {
+		ret = ethnl_update_bitset(eee.advertised,
+					  __ETHTOOL_LINK_MODE_MASK_NBITS,
+					  tb[ETHTOOL_A_EEE_MODES_OURS],
+					  link_mode_names, info->extack, &mod);
+		if (ret < 0)
+			return ret;
+	}
+
+	if (tb[ETHTOOL_A_EEE_ENABLED])
+		ethnl_update_bool(&eee.eee_enabled, tb[ETHTOOL_A_EEE_ENABLED], &mod);
+
+	if (tb[ETHTOOL_A_EEE_TX_LPI_ENABLED])
+		ethnl_update_bool(&eee.tx_lpi_enabled, tb[ETHTOOL_A_EEE_TX_LPI_ENABLED],
+				  &mod);
+
+	if (tb[ETHTOOL_A_EEE_TX_LPI_TIMER])
+		ethnl_update_u32(&eee.tx_lpi_timer, tb[ETHTOOL_A_EEE_TX_LPI_TIMER],
+				 &mod);
+
 	if (!mod)
 		return 0;
 
-- 
2.49.0

Re: [PATCH v0] net: ethtool: Only set supplied eee ethtool settings

[Andrew Lunn]

On Thu, Apr 17, 2025 at 10:12:30AM +1200, Rutger van Kruiningen wrote:
> Originally all ethtool eee setting updates were attempted even if the
> settings were not supplied, causing a null pointer crash.
> 
> Add check for each eee setting and only update if it exists.

I see what you mean, but i'm somewhat surprised we have not seen this
crash. Do you have a simple reproducer? I just did

ethtool --debug 255 --set-eee eth0 eee on

and it did not crash, despite:

sending genetlink packet (44 bytes):
    msg length 44 ethool ETHTOOL_MSG_EEE_SET
    ETHTOOL_MSG_EEE_SET
        ETHTOOL_A_EEE_HEADER
            ETHTOOL_A_HEADER_DEV_NAME = "eth0"
        ETHTOOL_A_EEE_ENABLED = on

So it only provided ETHTOOL_A_EEE_ENABLED and none of the others.

	Andrew

Re: [PATCH v0] net: ethtool: Only set supplied eee ethtool settings

[Rutger van Kruiningen]

On Thu, 2025-04-17 at 00:36 +0200, Andrew Lunn wrote:
> On Thu, Apr 17, 2025 at 10:12:30AM +1200, Rutger van Kruiningen
> wrote:
> > Originally all ethtool eee setting updates were attempted even if
> > the
> > settings were not supplied, causing a null pointer crash.
> > 
> > Add check for each eee setting and only update if it exists.
> 
> I see what you mean, but i'm somewhat surprised we have not seen this
> crash. Do you have a simple reproducer? I just did
> 
> ethtool --debug 255 --set-eee eth0 eee on
> 
> and it did not crash, despite:
> 
> sending genetlink packet (44 bytes):
>     msg length 44 ethool ETHTOOL_MSG_EEE_SET
>     ETHTOOL_MSG_EEE_SET
>         ETHTOOL_A_EEE_HEADER
>             ETHTOOL_A_HEADER_DEV_NAME = "eth0"
>         ETHTOOL_A_EEE_ENABLED = on
> 
> So it only provided ETHTOOL_A_EEE_ENABLED and none of the others.
> 
>         Andrew
Sorry it seems that there actually isn't a problem here. I thought the
bug I had was related to this but it must have been for something else
and was fixed at the same time of adding this code.

You can disreguard this patch.

Thanks, Rutger.