linux-kernel - [PATCH] cpufreq: mediatek: guard error paths to avoid kernel panic

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Date:   Thu, 23 Mar 2023 11:04:23 +0000
From:   Daniel Golle <daniel@...rotopia.org>
To:     linux-pm@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
Cc:     Sam Shih <sam.shih@...iatek.com>, John Crispin <john@...ozen.org>
Subject: [PATCH] cpufreq: mediatek: guard error paths to avoid kernel panic

Guard pointer access in error path of mtk_cpu_dvfs_info_init() to
make sure info->proc_reg and info->sram_reg are valid pointers before
accessing them, which would result in kernel panic e.g. in case of
them being set to -EPROBE_DEFER.

Fixes: 4b9ceb757bbb ("cpufreq: mediatek: Enable clocks and regulators")
Reported-by: Sam Shih <sam.shih@...iatek.com>
Suggested-by: Sam Shih <sam.shih@...iatek.com>
Signed-off-by: Daniel Golle <daniel@...rotopia.org>
---
 drivers/cpufreq/mediatek-cpufreq.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/mediatek-cpufreq.c b/drivers/cpufreq/mediatek-cpufreq.c
index 4466d0c91a6a..980a31ddd0f2 100644
--- a/drivers/cpufreq/mediatek-cpufreq.c
+++ b/drivers/cpufreq/mediatek-cpufreq.c
@@ -579,10 +579,12 @@ static int mtk_cpu_dvfs_info_init(struct mtk_cpu_dvfs_info *info, int cpu)
 	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))
-		regulator_disable(info->sram_reg);
+	if (!IS_ERR(info->proc_reg))
+		if (regulator_is_enabled(info->proc_reg))
+			regulator_disable(info->proc_reg);
+	if (!IS_ERR(info->sram_reg))
+		if (info->sram_reg && regulator_is_enabled(info->sram_reg))
+			regulator_disable(info->sram_reg);
 
 	if (!IS_ERR(info->proc_reg))
 		regulator_put(info->proc_reg);
-- 
2.40.0