[PATCH AUTOSEL 5.15 27/46] drm/amd/display: fix array index out of bound error in bios parser

[Sasha Levin <sashal@kernel.org>]

From: Aurabindo Pillai <aurabindo.pillai@amd.com>

[ Upstream commit 4fc1ba4aa589ca267468ad23fedef37562227d32 ]

[Why&How]
Firmware headers dictate that gpio_pin array only has a size of 8. The
count returned from vbios however is greater than 8.

Fix this by not using array indexing but incrementing the pointer since
gpio_pin definition in atomfirmware.h is hardcoded to size 8

Reviewed-by: Martin Leung <Martin.Leung@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 .../gpu/drm/amd/display/dc/bios/bios_parser2.c   | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c b/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c
index 6dbde74c1e06..1d86fd5610c0 100644
--- a/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c
+++ b/drivers/gpu/drm/amd/display/dc/bios/bios_parser2.c
@@ -352,6 +352,7 @@ static enum bp_result get_gpio_i2c_info(
 	uint32_t count = 0;
 	unsigned int table_index = 0;
 	bool find_valid = false;
+	struct atom_gpio_pin_assignment *pin;
 
 	if (!info)
 		return BP_RESULT_BADINPUT;
@@ -379,20 +380,17 @@ static enum bp_result get_gpio_i2c_info(
 			- sizeof(struct atom_common_table_header))
 				/ sizeof(struct atom_gpio_pin_assignment);
 
+	pin = (struct atom_gpio_pin_assignment *) header->gpio_pin;
+
 	for (table_index = 0; table_index < count; table_index++) {
-		if (((record->i2c_id & I2C_HW_CAP) == (
-		header->gpio_pin[table_index].gpio_id &
-						I2C_HW_CAP)) &&
-		((record->i2c_id & I2C_HW_ENGINE_ID_MASK)  ==
-		(header->gpio_pin[table_index].gpio_id &
-					I2C_HW_ENGINE_ID_MASK)) &&
-		((record->i2c_id & I2C_HW_LANE_MUX) ==
-		(header->gpio_pin[table_index].gpio_id &
-						I2C_HW_LANE_MUX))) {
+		if (((record->i2c_id & I2C_HW_CAP) 				== (pin->gpio_id & I2C_HW_CAP)) &&
+		    ((record->i2c_id & I2C_HW_ENGINE_ID_MASK)	== (pin->gpio_id & I2C_HW_ENGINE_ID_MASK)) &&
+		    ((record->i2c_id & I2C_HW_LANE_MUX) 		== (pin->gpio_id & I2C_HW_LANE_MUX))) {
 			/* still valid */
 			find_valid = true;
 			break;
 		}
+		pin = (struct atom_gpio_pin_assignment *)((uint8_t *)pin + sizeof(struct atom_gpio_pin_assignment));
 	}
 
 	/* If we don't find the entry that we are looking for then
-- 
2.35.1