From ccc514b7e7acbd301219cbaec0fc0bfe5741acee Mon Sep 17 00:00:00 2001
From: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Date: Mon, 5 Feb 2024 16:54:10 +0530
Subject: [PATCH] drm/amd/display: Fix possible buffer overflow in 'find_dcfclk_for_voltage()'
Git-commit: ccc514b7e7acbd301219cbaec0fc0bfe5741acee
Patch-mainline: v6.8-rc5
References: git-fixes
Alt-commit: 9ab1a996dc7f492d5dea51b7c163c92a524eaf00

when 'find_dcfclk_for_voltage()' function is looping over
VG_NUM_SOC_VOLTAGE_LEVELS (which is 8), but the size of the DcfClocks
array is VG_NUM_DCFCLK_DPM_LEVELS (which is 7).

When the loop variable i reaches 7, the function tries to access
clock_table->DcfClocks[7]. However, since the size of the DcfClocks
array is 7, the valid indices are 0 to 6. Index 7 is beyond the size of
the array, leading to a buffer overflow.

Reported by smatch & thus fixing the below:
drivers/gpu/drm/amd/amdgpu/../display/dc/clk_mgr/dcn301/vg_clk_mgr.c:550 find_dcfclk_for_voltage() error: buffer overflow 'clock_table->DcfClocks' 7 <= 7

Fixes: 3a83e4e64bb1 ("drm/amd/display: Add dcn3.01 support to DC (v2)")
Cc: Roman Li <Roman.Li@amd.com>
Cc: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Cc: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Roman Li <roman.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/amd/display/dc/clk_mgr/dcn301/vg_clk_mgr.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn301/vg_clk_mgr.c b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn301/vg_clk_mgr.c
index a5489fe6875f..aa9fd1dc550a 100644
--- a/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn301/vg_clk_mgr.c
+++ b/drivers/gpu/drm/amd/display/dc/clk_mgr/dcn301/vg_clk_mgr.c
@@ -546,6 +546,8 @@ static unsigned int find_dcfclk_for_voltage(const struct vg_dpm_clocks *clock_ta
 	int i;
 
 	for (i = 0; i < VG_NUM_SOC_VOLTAGE_LEVELS; i++) {
+		if (i >= VG_NUM_DCFCLK_DPM_LEVELS)
+			break;
 		if (clock_table->SocVoltage[i] == voltage)
 			return clock_table->DcfClocks[i];
 	}
-- 
2.35.3