openwrt/target/linux/mediatek/patches-5.15/350-18-cpufreq-mediatek-fix-KP-caused-by-handler-usage-afte.patch

From fced531b7c7e18192e7982637c8e8f20c29aad64 Mon Sep 17 00:00:00 2001
From: Jia-Wei Chang <jia-wei.chang@mediatek.com>
Date: Fri, 24 Mar 2023 18:11:28 +0800
Subject: [PATCH 18/21] cpufreq: mediatek: fix KP caused by handler usage after
 regulator_put/clk_put

Any kind of failure in mtk_cpu_dvfs_info_init() will lead to calling
regulator_put() or clk_put() and the KP will occur since the regulator/clk
handlers are used after released in mtk_cpu_dvfs_info_release().

To prevent the usage after regulator_put()/clk_put(), the regulator/clk
handlers are addressed in a way of "Free the Last Thing Style".

Signed-off-by: Jia-Wei Chang <jia-wei.chang@mediatek.com>
Fixes: 4b9ceb757bbb ("cpufreq: mediatek: Enable clocks and regulators")
Suggested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Suggested-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/mediatek-cpufreq.c | 62 +++++++++++++++---------------
 1 file changed, 30 insertions(+), 32 deletions(-)

--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -420,7 +420,7 @@ static int mtk_cpu_dvfs_info_init(struct
 		ret = PTR_ERR(info->inter_clk);
 		dev_err_probe(cpu_dev, ret,
 			      "cpu%d: failed to get intermediate clk\n", cpu);
-		goto out_free_resources;
+		goto out_free_mux_clock;
 	}
 
 	info->proc_reg = regulator_get_optional(cpu_dev, "proc");
@@ -428,13 +428,13 @@ static int mtk_cpu_dvfs_info_init(struct
 		ret = PTR_ERR(info->proc_reg);
 		dev_err_probe(cpu_dev, ret,
 			      "cpu%d: failed to get proc regulator\n", cpu);
-		goto out_free_resources;
+		goto out_free_inter_clock;
 	}
 
 	ret = regulator_enable(info->proc_reg);
 	if (ret) {
 		dev_warn(cpu_dev, "cpu%d: failed to enable vproc\n", cpu);
-		goto out_free_resources;
+		goto out_free_proc_reg;
 	}
 
 	/* Both presence and absence of sram regulator are valid cases. */
@@ -442,14 +442,14 @@ static int mtk_cpu_dvfs_info_init(struct
 	if (IS_ERR(info->sram_reg)) {
 		ret = PTR_ERR(info->sram_reg);
 		if (ret == -EPROBE_DEFER)
-			goto out_free_resources;
+			goto out_disable_proc_reg;
 
 		info->sram_reg = NULL;
 	} else {
 		ret = regulator_enable(info->sram_reg);
 		if (ret) {
 			dev_warn(cpu_dev, "cpu%d: failed to enable vsram\n", cpu);
-			goto out_free_resources;
+			goto out_free_sram_reg;
 		}
 	}
 
@@ -458,13 +458,13 @@ static int mtk_cpu_dvfs_info_init(struct
 	if (ret) {
 		dev_err(cpu_dev,
 			"cpu%d: failed to get OPP-sharing information\n", cpu);
-		goto out_free_resources;
+		goto out_disable_sram_reg;
 	}
 
 	ret = dev_pm_opp_of_cpumask_add_table(&info->cpus);
 	if (ret) {
 		dev_warn(cpu_dev, "cpu%d: no OPP table\n", cpu);
-		goto out_free_resources;
+		goto out_disable_sram_reg;
 	}
 
 	ret = clk_prepare_enable(info->cpu_clk);
@@ -533,43 +533,41 @@ out_disable_mux_clock:
 out_free_opp_table:
 	dev_pm_opp_of_cpumask_remove_table(&info->cpus);
 
-out_free_resources:
-	if (regulator_is_enabled(info->proc_reg))
-		regulator_disable(info->proc_reg);
-	if (info->sram_reg && regulator_is_enabled(info->sram_reg))
+out_disable_sram_reg:
+	if (info->sram_reg)
 		regulator_disable(info->sram_reg);
 
-	if (!IS_ERR(info->proc_reg))
-		regulator_put(info->proc_reg);
-	if (!IS_ERR(info->sram_reg))
+out_free_sram_reg:
+	if (info->sram_reg)
 		regulator_put(info->sram_reg);
-	if (!IS_ERR(info->cpu_clk))
-		clk_put(info->cpu_clk);
-	if (!IS_ERR(info->inter_clk))
-		clk_put(info->inter_clk);
+
+out_disable_proc_reg:
+	regulator_disable(info->proc_reg);
+
+out_free_proc_reg:
+	regulator_put(info->proc_reg);
+
+out_free_inter_clock:
+	clk_put(info->inter_clk);
+
+out_free_mux_clock:
+	clk_put(info->cpu_clk);
 
 	return ret;
 }
 
 static void mtk_cpu_dvfs_info_release(struct mtk_cpu_dvfs_info *info)
 {
-	if (!IS_ERR(info->proc_reg)) {
-		regulator_disable(info->proc_reg);
-		regulator_put(info->proc_reg);
-	}
-	if (!IS_ERR(info->sram_reg)) {
+	regulator_disable(info->proc_reg);
+	regulator_put(info->proc_reg);
+	if (info->sram_reg) {
 		regulator_disable(info->sram_reg);
 		regulator_put(info->sram_reg);
 	}
-	if (!IS_ERR(info->cpu_clk)) {
-		clk_disable_unprepare(info->cpu_clk);
-		clk_put(info->cpu_clk);
-	}
-	if (!IS_ERR(info->inter_clk)) {
-		clk_disable_unprepare(info->inter_clk);
-		clk_put(info->inter_clk);
-	}
-
+	clk_disable_unprepare(info->cpu_clk);
+	clk_put(info->cpu_clk);
+	clk_disable_unprepare(info->inter_clk);
+	clk_put(info->inter_clk);
 	dev_pm_opp_of_cpumask_remove_table(&info->cpus);
 	dev_pm_opp_unregister_notifier(info->cpu_dev, &info->opp_nb);
 }