[PATCH AUTOSEL 4.19 14/26] drm/amd/display: Guard against NULL pointer deref when get_i2c_info fails

Sasha Levin sashal at kernel.org
Wed Feb 24 12:54:22 UTC 2021

From: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>

[ Upstream commit 44a09e3d95bd2b7b0c224100f78f335859c4e193 ]

If the BIOS table is invalid or corrupt then get_i2c_info can fail
and we dereference a NULL pointer.

Check that ddc_pin is not NULL before using it and log an error if it
is because this is unexpected.

Tested-by: Daniel Wheeler <daniel.wheeler at amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
Reviewed-by: Eric Yang <eric.yang2 at amd.com>
Acked-by: Anson Jacob <anson.jacob at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Sasha Levin <sashal at kernel.org>
 drivers/gpu/drm/amd/display/dc/core/dc_link.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index fa0e6c8e2447c..e3bedf4cc9c03 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -1124,6 +1124,11 @@ static bool construct(
 		goto ddc_create_fail;
+	if (!link->ddc->ddc_pin) {
+		DC_ERROR("Failed to get I2C info for connector!\n");
+		goto ddc_create_fail;
+	}
 	link->ddc_hw_inst =

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