[PATCH 07/16] drm/amd/display: Guard against NULL pointer deref when get_i2c_info fails

[Anson Jacob]

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

[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.

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>
---
 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 c7d6ceb8fed8..8b2d387a46dc 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -1478,6 +1478,11 @@ static bool dc_link_construct(struct dc_link *link,
 		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));
 
-- 
2.25.1