From: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Date: Fri, 18 Dec 2020 17:14:00 +0000 (-0500)
Subject: drm/amd/display: Guard against NULL pointer deref when get_i2c_info fails
X-Git-Tag: v4.19.179~20
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=5886337edaa8d0a1459054452661d46f2ab0a2e2;p=thirdparty%2Fkernel%2Fstable.git

drm/amd/display: Guard against NULL pointer deref when get_i2c_info fails

[ Upstream commit 44a09e3d95bd2b7b0c224100f78f335859c4e193 ]

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

[How]
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@amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Eric Yang <eric.yang2@amd.com>
Acked-by: Anson Jacob <anson.jacob@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

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 =
 		dal_ddc_get_line(
 			dal_ddc_service_get_ddc_pin(link->ddc));