This is a note to let you know that I've just added the patch titled drm/amd/display: Guard against NULL pointer deref when get_i2c_info fails to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drm-amd-display-guard-against-null-pointer-deref-whe.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 5139ed7e0c5b79b5c46a651d4465eb11019f8865 Author: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx> Date: Fri Dec 18 12:14:00 2020 -0500 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@xxxxxxx> Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@xxxxxxx> Reviewed-by: Eric Yang <eric.yang2@xxxxxxx> Acked-by: Anson Jacob <anson.jacob@xxxxxxx> Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> 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 fa92b88bc5a1..40041c61a100 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c @@ -1303,6 +1303,11 @@ 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));