From 217f64f348c90cba62164e7ff38e0ccf78a5ca09 Mon Sep 17 00:00:00 2001 From: Hari Mishal Date: Wed, 16 Sep 2026 16:23:32 +0200 Subject: drm/amd/display: guard dc_sink dereferences in MST mode validation dm_dp_mst_is_port_support_mode() reads aconnector->dc_sink->dsc_caps... for the DSC branch-throughput check, and get_conv_frl_bw()'s HDMI-PCON FRL-bandwidth path reads aconnector->dc_sink->edid_caps.max_frl_rate, both without a NULL check. dc_sink is cleared asynchronously on MST unplug, and both functions run from paths that the driver's own comments document as racing that teardown: the connector probe worker's ->mode_valid callback and a compositor's atomic check, neither of which holds the MST manager lock that the teardown path uses. The former does have an existing dsc_aux NULL check, but dsc_aux isn't reliably cleared in every path that clears dc_sink, so it doesn't cover this. Fail the port-support check and skip the FRL conversion path when the sink is already gone. Fixes: f04d275d94e1 ("drm/amd/display: add mst port output bw check") Fixes: 5c9b8b27a883 ("drm/amd/display: Tie FRL support into amdgpu_dm") Assisted-by: gkh_clanker_t1000 Signed-off-by: Hari Mishal Reviewed-by: Fangzhi Zuo Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher (cherry picked from commit 7c3db8da4e039698ae198c870712428644e965c7) Cc: stable@vger.kernel.org --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c index 045a7f88b..7261317d4 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_mst_types.c @@ -1231,7 +1231,8 @@ static bool get_conv_frl_bw(struct amdgpu_dm_connector *aconnector, unsigned int max_sink_bw_in_kbps = 0; unsigned int dsc_max_sink_bw_in_kbps = 0; - if (aconnector->dc_link->dc->caps.dp_hdmi21_pcon_support && + if (aconnector->dc_sink && + aconnector->dc_link->dc->caps.dp_hdmi21_pcon_support && aconnector->mst_downstream_port_caps.bytes.byte0.bits.DWN_STRM_PORTX_TYPE == DOWN_STREAM_DETAILED_HDMI) { max_conv_bw_in_kbps = dc_link_bw_kbps_from_raw_frl_link_rate_data( aconnector->dc_link->dc, @@ -1996,6 +1997,9 @@ enum dc_status dm_dp_mst_is_port_support_mode( struct dc_dsc_config_options dsc_options = {0}; uint32_t stream_kbps; + if (!aconnector->dc_sink) + return DC_FAIL_BANDWIDTH_VALIDATE; + /* DSC unnecessary case * Check if timing could be supported within end-to-end BW */ -- cgit v1.3.1