net/mlx5e: Correct snprintf truncation handling for fw_version buffer

snprintf returns the length of the formatted string, excluding the trailing
null, without accounting for truncation. This means that is the return
value is greater than or equal to the size parameter, the fw_version string
was truncated.

Reported-by: David Laight <[email protected]>
Closes: https://lore.kernel.org/netdev/[email protected]/
Link: https://docs.kernel.org/core-api/kernel-api.html#c.snprintf
Fixes: 41e63c2 ("net/mlx5e: Check return value of snprintf writing to fw_version buffer")
Signed-off-by: Rahul Rameshbabu <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Signed-off-by: Saeed Mahameed <[email protected]>

Author: Binary-Eater

drivers/net/ethernet/mellanox/mlx5/core/en_ethtool.c

@@ -49,7 +49,7 @@ void mlx5e_ethtool_get_drvinfo(struct mlx5e_priv *priv,
 	count = snprintf(drvinfo->fw_version, sizeof(drvinfo->fw_version),
 			 "%d.%d.%04d (%.16s)", fw_rev_maj(mdev),
 			 fw_rev_min(mdev), fw_rev_sub(mdev), mdev->board_id);
-	if (count == sizeof(drvinfo->fw_version))
+	if (count >= sizeof(drvinfo->fw_version))
 		snprintf(drvinfo->fw_version, sizeof(drvinfo->fw_version),
 			 "%d.%d.%04d", fw_rev_maj(mdev),
 			 fw_rev_min(mdev), fw_rev_sub(mdev));