[PATCH net] net: ethtool: Handle missing cable test TDR parameters

[Andrew Lunn]

A last minute change put the TDR cable test parameters into a nest.
The validation is not sufficient, resulting in an oops if the nest is
missing. Set default values first, then update them if the nest is
provided.

Fixes: f2bc8ad31a7f ("net: ethtool: Allow PHY cable test TDR data to 
configured")
Signed-off-by: Andrew Lunn <and...@lunn.ch>
---
 net/ethtool/cabletest.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/net/ethtool/cabletest.c b/net/ethtool/cabletest.c
index 7b7a0456c15c..7194956aa09e 100644
--- a/net/ethtool/cabletest.c
+++ b/net/ethtool/cabletest.c
@@ -234,6 +234,14 @@ static int ethnl_act_cable_test_tdr_cfg(const struct 
nlattr *nest,
        struct nlattr *tb[ETHTOOL_A_CABLE_TEST_TDR_CFG_MAX + 1];
        int ret;
 
+       cfg->first = 100;
+       cfg->step = 100;
+       cfg->last = MAX_CABLE_LENGTH_CM;
+       cfg->pair = PHY_PAIR_ALL;
+
+       if (!nest)
+               return 0;
+
        ret = nla_parse_nested(tb, ETHTOOL_A_CABLE_TEST_TDR_CFG_MAX, nest,
                               cable_test_tdr_act_cfg_policy, info->extack);
        if (ret < 0)
@@ -242,17 +250,12 @@ static int ethnl_act_cable_test_tdr_cfg(const struct 
nlattr *nest,
        if (tb[ETHTOOL_A_CABLE_TEST_TDR_CFG_FIRST])
                cfg->first = nla_get_u32(
                        tb[ETHTOOL_A_CABLE_TEST_TDR_CFG_FIRST]);
-       else
-               cfg->first = 100;
+
        if (tb[ETHTOOL_A_CABLE_TEST_TDR_CFG_LAST])
                cfg->last = nla_get_u32(tb[ETHTOOL_A_CABLE_TEST_TDR_CFG_LAST]);
-       else
-               cfg->last = MAX_CABLE_LENGTH_CM;
 
        if (tb[ETHTOOL_A_CABLE_TEST_TDR_CFG_STEP])
                cfg->step = nla_get_u32(tb[ETHTOOL_A_CABLE_TEST_TDR_CFG_STEP]);
-       else
-               cfg->step = 100;
 
        if (tb[ETHTOOL_A_CABLE_TEST_TDR_CFG_PAIR]) {
                cfg->pair = nla_get_u8(tb[ETHTOOL_A_CABLE_TEST_TDR_CFG_PAIR]);
@@ -263,8 +266,6 @@ static int ethnl_act_cable_test_tdr_cfg(const struct nlattr 
*nest,
                                "invalid pair parameter");
                        return -EINVAL;
                }
-       } else {
-               cfg->pair = PHY_PAIR_ALL;
        }
 
        if (cfg->first > MAX_CABLE_LENGTH_CM) {
-- 
2.27.0.rc2