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From:   Bartosz Szczepanek <bsz@semihalf.com>
To:     Matthew Garrett <mjg59@google.com>,
        Zhang Rui <rui.zhang@intel.com>,
        Pandruvada Srinivas <srinivas.pandruvada@linux.intel.com>,
        linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Daniel Lezcano <daniel.lezcano@linaro.org>,
        Amit Kucheria <amit.kucheria@verdurent.com>,
        Radoslaw Biernacki <rad@semihalf.com>,
        Alex Levin <levinale@google.com>,
        Bartosz Szczepanek <bsz@semihalf.com>
Subject: [PATCH] thermal/int340x_thermal: Prevent page fault on .set_mode() op
Date:   Wed,  8 Jul 2020 15:46:13 +0200
Message-Id: <20200708134613.131555-1-bsz@semihalf.com>
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Sender: linux-kernel-owner@vger.kernel.org
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Starting from commit "thermal/int340x_thermal: Don't require IDSP to
exist", priv->current_uuid_index is initialized to -1. This value may
be passed to int3400_thermal_run_osc() from int3400_thermal_set_mode,
contributing to page fault when accessing int3400_thermal_uuids array
at index -1.

This commit adds a check on uuid value to int3400_thermal_run_osc.

Signed-off-by: Bartosz Szczepanek <bsz@semihalf.com>
---
 drivers/thermal/intel/int340x_thermal/int3400_thermal.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/thermal/intel/int340x_thermal/int3400_thermal.c b/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
index 0b3a62655843..12448ccd27f1 100644
--- a/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
+++ b/drivers/thermal/intel/int340x_thermal/int3400_thermal.c
@@ -216,11 +216,16 @@ static int int3400_thermal_run_osc(acpi_handle handle,
 	acpi_status status;
 	int result = 0;
 	struct acpi_osc_context context = {
-		.uuid_str = int3400_thermal_uuids[uuid],
+		.uuid_str = NULL,
 		.rev = 1,
 		.cap.length = 8,
 	};
 
+	if (uuid < 0 || uuid >= INT3400_THERMAL_MAXIMUM_UUID)
+		return -EINVAL;
+
+	context.uuid_str = int3400_thermal_uuids[uuid];
+
 	buf[OSC_QUERY_DWORD] = 0;
 	buf[OSC_SUPPORT_DWORD] = enable;
 
-- 
2.17.1