4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Imre Deak <imre.deak@xxxxxxxxx> commit 448421b5e93b9177c5698f0cf6f5e72d2995eeca upstream. Handle any error due to partial reads, timeouts etc. to avoid parsing uninitialized data subsequently. Also bail out if the parsing itself fails. Cc: Dave Airlie <airlied@xxxxxxxxxx> Cc: Lyude <lyude@xxxxxxxxxx> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx> Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> Reviewed-by: Lyude <lyude@xxxxxxxxxx> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxx> Link: https://patchwork.freedesktop.org/patch/msgid/20170719114330.26540-2-imre.deak@xxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/drm_dp_mst_topology.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -2200,11 +2200,17 @@ static void drm_dp_get_one_sb_msg(struct ret = drm_dp_dpcd_read(mgr->aux, basereg + curreply, replyblock, len); if (ret != len) { - DRM_DEBUG_KMS("failed to read a chunk\n"); + DRM_DEBUG_KMS("failed to read a chunk (len %d, ret %d)\n", + len, ret); + return; } + ret = drm_dp_sideband_msg_build(msg, replyblock, len, false); - if (ret == false) + if (!ret) { DRM_DEBUG_KMS("failed to build sideband msg\n"); + return; + } + curreply += len; replylen -= len; }