[PATCH net] net: phy: marvell: Fix buffer overrun with stats counters

[Andrew Lunn]

marvell_get_sset_count() returns how many statistics counters there
are. If the PHY supports fibre, there are 3, otherwise two.

marvell_get_strings() does not make this distinction, and always
returns 3 strings. This then often results in writing passed the end
of the buffer for the strings.

Fixes: 2170fef78a40 ("Marvell phy: add field to get errors from fiber link.")
Signed-off-by: Andrew Lunn <and...@lunn.ch>
---
 drivers/net/phy/marvell.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/phy/marvell.c b/drivers/net/phy/marvell.c
index 3ccba37bd6dd..f76c4048b978 100644
--- a/drivers/net/phy/marvell.c
+++ b/drivers/net/phy/marvell.c
@@ -1489,9 +1489,10 @@ static int marvell_get_sset_count(struct phy_device 
*phydev)
 
 static void marvell_get_strings(struct phy_device *phydev, u8 *data)
 {
+       int count = marvell_get_sset_count(phydev);
        int i;
 
-       for (i = 0; i < ARRAY_SIZE(marvell_hw_stats); i++) {
+       for (i = 0; i < count; i++) {
                strlcpy(data + i * ETH_GSTRING_LEN,
                        marvell_hw_stats[i].string, ETH_GSTRING_LEN);
        }
@@ -1519,9 +1520,10 @@ static u64 marvell_get_stat(struct phy_device *phydev, 
int i)
 static void marvell_get_stats(struct phy_device *phydev,
                              struct ethtool_stats *stats, u64 *data)
 {
+       int count = marvell_get_sset_count(phydev);
        int i;
 
-       for (i = 0; i < ARRAY_SIZE(marvell_hw_stats); i++)
+       for (i = 0; i < count; i++)
                data[i] = marvell_get_stat(phydev, i);
 }
 
-- 
2.20.1