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authorImre Deak <imre.deak@intel.com>2017-07-19 16:46:32 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-07-27 15:10:22 -0700
commit255758f79390097c94c9dc2695991e4662041547 (patch)
tree4bdebff24ccd68807040ab7bd6bd755324487eb2
parent4c5cea159d3f6c5da6f23761e46efc230c81338b (diff)
drm/mst: Avoid processing partially received up/down message transactions
commit 636c4c3e762b62aa93632c645ca65879285b16e3 upstream. 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 <airlied@redhat.com> Cc: Lyude <lyude@redhat.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Imre Deak <imre.deak@intel.com> Reviewed-by: Lyude <lyude@redhat.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20170719134632.13366-1-imre.deak@intel.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/gpu/drm/drm_dp_mst_topology.c31
1 files changed, 24 insertions, 7 deletions
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index 89cd38d254a5..e86d3a5badf4 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;