[4.19,33/52] drm/amd/display: Guard against NULL pointer deref when get_i2c_info fails
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Message ID 20210305120855.298573239@linuxfoundation.org
State New, archived
Headers show
Series
  • Untitled series #487861
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Commit Message

Greg Kroah-Hartman March 5, 2021, 12:22 p.m. UTC
From: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>

[ 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>
---
 drivers/gpu/drm/amd/display/dc/core/dc_link.c | 5 +++++
 1 file changed, 5 insertions(+)

Patch
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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 fa0e6c8e2447..e3bedf4cc9c0 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));