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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Evan Quan <evan.quan@amd.com>,
        =?UTF-8?q?Andr=C3=A9=20Almeida?= <andrealmeid@igalia.com>,
        Yefim Barashkin <mr.b34r@kolabnow.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 098/167] drm/amd/pm: Prevent divide by zero
Date:   Tue, 19 Jul 2022 13:53:50 +0200
Message-Id: <20220719114705.929728889@linuxfoundation.org>
In-Reply-To: <20220719114656.750574879@linuxfoundation.org>
References: <20220719114656.750574879@linuxfoundation.org>
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From: Yefim Barashkin <mr.b34r@kolabnow.com>

[ Upstream commit 0638c98c17aa12fe914459c82cd178247e21fb2b ]

divide error: 0000 [#1] SMP PTI
CPU: 3 PID: 78925 Comm: tee Not tainted 5.15.50-1-lts #1
Hardware name: MSI MS-7A59/Z270 SLI PLUS (MS-7A59), BIOS 1.90 01/30/2018
RIP: 0010:smu_v11_0_set_fan_speed_rpm+0x11/0x110 [amdgpu]

Speed is user-configurable through a file.
I accidentally set it to zero, and the driver crashed.

Reviewed-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Signed-off-by: Yefim Barashkin <mr.b34r@kolabnow.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c b/drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c
index e6c93396434f..614c3d049514 100644
--- a/drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c
+++ b/drivers/gpu/drm/amd/pm/swsmu/smu11/smu_v11_0.c
@@ -1235,6 +1235,8 @@ int smu_v11_0_set_fan_speed_rpm(struct smu_context *smu,
 	uint32_t crystal_clock_freq = 2500;
 	uint32_t tach_period;
 
+	if (speed == 0)
+		return -EINVAL;
 	/*
 	 * To prevent from possible overheat, some ASICs may have requirement
 	 * for minimum fan speed:
-- 
2.35.1