From 448421b5e93b9177c5698f0cf6f5e72d2995eeca Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Wed, 19 Jul 2017 14:43:28 +0300 Subject: drm/mst: Fix error handling during MST sideband message reception 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 Cc: Lyude Cc: Daniel Vetter Signed-off-by: Imre Deak Reviewed-by: Lyude Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20170719114330.26540-2-imre.deak@intel.com --- drivers/gpu/drm/drm_dp_mst_topology.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'drivers/gpu/drm/drm_dp_mst_topology.c') diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index bfd237c..ce0e584 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -2196,11 +2196,17 @@ static void drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up) 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; } -- cgit v1.1 From 7f8b3987da54cb4d41ad2545cd4d7958b9a36bdf Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Wed, 19 Jul 2017 14:43:29 +0300 Subject: drm/mst: Avoid dereferencing a NULL mstb in drm_dp_mst_handle_up_req() In case of an unknown broadcast message is sent mstb will remain unset, so check for this. Cc: Dave Airlie Cc: Lyude Cc: Daniel Vetter Signed-off-by: Imre Deak Reviewed-by: Lyude Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20170719114330.26540-3-imre.deak@intel.com --- drivers/gpu/drm/drm_dp_mst_topology.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'drivers/gpu/drm/drm_dp_mst_topology.c') diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index ce0e584..7a62011 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -2324,7 +2324,9 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr) DRM_DEBUG_KMS("Got RSN: pn: %d avail_pbn %d\n", msg.u.resource_stat.port_number, msg.u.resource_stat.available_pbn); } - drm_dp_put_mst_branch_device(mstb); + if (mstb) + drm_dp_put_mst_branch_device(mstb); + memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx)); } return ret; -- cgit v1.1 From 636c4c3e762b62aa93632c645ca65879285b16e3 Mon Sep 17 00:00:00 2001 From: Imre Deak Date: Wed, 19 Jul 2017 16:46:32 +0300 Subject: drm/mst: Avoid processing partially received up/down message transactions Currently we may process up/down message transactions containing uninitialized data. This can happen if there was an error during the reception of any message in the transaction, but we happened to receive the last message correctly with the end-of-message flag set. To avoid this abort the reception of the transaction when the first error is detected, rejecting any messages until a message with the start-of-message flag is received (which will start a new transaction). This is also what the DP 1.4 spec 2.11.8.2 calls for in this case. In addtion this also prevents receiving bogus transactions without the first message with the the start-of-message flag set. v2: - unchanged v3: - git add the part that actually skips messages after an error in drm_dp_sideband_msg_build() Cc: Dave Airlie Cc: Lyude Cc: Daniel Vetter Signed-off-by: Imre Deak Reviewed-by: Lyude Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20170719134632.13366-1-imre.deak@intel.com --- drivers/gpu/drm/drm_dp_mst_topology.c | 31 ++++++++++++++++++++++++------- 1 file changed, 24 insertions(+), 7 deletions(-) (limited to 'drivers/gpu/drm/drm_dp_mst_topology.c') diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 7a62011..ae5f068 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -330,6 +330,13 @@ static bool drm_dp_sideband_msg_build(struct drm_dp_sideband_msg_rx *msg, return false; } + /* + * ignore out-of-order messages or messages that are part of a + * failed transaction + */ + if (!recv_hdr.somt && !msg->have_somt) + return false; + /* get length contained in this portion */ msg->curchunk_len = recv_hdr.msg_len; msg->curchunk_hdrlen = hdrlen; @@ -2164,7 +2171,7 @@ out_unlock: } EXPORT_SYMBOL(drm_dp_mst_topology_mgr_resume); -static void drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up) +static bool drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up) { int len; u8 replyblock[32]; @@ -2179,12 +2186,12 @@ static void drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up) replyblock, len); if (ret != len) { DRM_DEBUG_KMS("failed to read DPCD down rep %d %d\n", len, ret); - return; + return false; } ret = drm_dp_sideband_msg_build(msg, replyblock, len, true); if (!ret) { DRM_DEBUG_KMS("sideband msg build failed %d\n", replyblock[0]); - return; + return false; } replylen = msg->curchunk_len + msg->curchunk_hdrlen; @@ -2198,25 +2205,30 @@ static void drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up) if (ret != len) { DRM_DEBUG_KMS("failed to read a chunk (len %d, ret %d)\n", len, ret); - return; + return false; } ret = drm_dp_sideband_msg_build(msg, replyblock, len, false); if (!ret) { DRM_DEBUG_KMS("failed to build sideband msg\n"); - return; + return false; } curreply += len; replylen -= len; } + return true; } static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr) { int ret = 0; - drm_dp_get_one_sb_msg(mgr, false); + if (!drm_dp_get_one_sb_msg(mgr, false)) { + memset(&mgr->down_rep_recv, 0, + sizeof(struct drm_dp_sideband_msg_rx)); + return 0; + } if (mgr->down_rep_recv.have_eomt) { struct drm_dp_sideband_msg_tx *txmsg; @@ -2272,7 +2284,12 @@ static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr) static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr) { int ret = 0; - drm_dp_get_one_sb_msg(mgr, true); + + if (!drm_dp_get_one_sb_msg(mgr, true)) { + memset(&mgr->up_req_recv, 0, + sizeof(struct drm_dp_sideband_msg_rx)); + return 0; + } if (mgr->up_req_recv.have_eomt) { struct drm_dp_sideband_msg_req_body msg; -- cgit v1.1