@@ -3700,8 +3700,7 @@ int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool ms
ret = 0;
mgr->payload_id_table_cleared = false;
- memset(&mgr->down_rep_recv, 0, sizeof(mgr->down_rep_recv));
- memset(&mgr->up_req_recv, 0, sizeof(mgr->up_req_recv));
+ mgr->reset_rx_state = true;
}
out_unlock:
@@ -3859,6 +3858,11 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr,
}
EXPORT_SYMBOL(drm_dp_mst_topology_mgr_resume);
+static void reset_msg_rx_state(struct drm_dp_sideband_msg_rx *msg)
+{
+ memset(msg, 0, sizeof(*msg));
+}
+
static bool
drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up,
struct drm_dp_mst_branch **mstb)
@@ -4141,6 +4145,17 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
return 0;
}
+static void update_msg_rx_state(struct drm_dp_mst_topology_mgr *mgr)
+{
+ mutex_lock(&mgr->lock);
+ if (mgr->reset_rx_state) {
+ mgr->reset_rx_state = false;
+ reset_msg_rx_state(&mgr->down_rep_recv);
+ reset_msg_rx_state(&mgr->up_req_recv);
+ }
+ mutex_unlock(&mgr->lock);
+}
+
/**
* drm_dp_mst_hpd_irq_handle_event() - MST hotplug IRQ handle MST event
* @mgr: manager to notify irq for.
@@ -4175,6 +4190,8 @@ int drm_dp_mst_hpd_irq_handle_event(struct drm_dp_mst_topology_mgr *mgr, const u
*handled = true;
}
+ update_msg_rx_state(mgr);
+
if (esi[1] & DP_DOWN_REP_MSG_RDY) {
ret = drm_dp_mst_handle_down_rep(mgr);
*handled = true;
@@ -699,6 +699,13 @@ struct drm_dp_mst_topology_mgr {
*/
bool payload_id_table_cleared : 1;
+ /**
+ * @reset_rx_state: The down request's reply and up request message
+ * receiver state must be reset, after the topology manager got
+ * removed. Protected by @lock.
+ */
+ bool reset_rx_state : 1;
+
/**
* @payload_count: The number of currently active payloads in hardware. This value is only
* intended to be used internally by MST helpers for payload tracking, and is only safe to
If the MST topology is removed during the reception of an MST down reply or MST up request sideband message, the drm_dp_mst_topology_mgr::up_req_recv/down_rep_recv states could be reset from one thread via drm_dp_mst_topology_mgr_set_mst(false), racing with the reading/parsing of the message from another thread via drm_dp_mst_handle_down_rep() or drm_dp_mst_handle_up_req(). The race is possible since the reader/parser doesn't hold any lock while accessing the reception state. This in turn can lead to a memory corruption in the reader/parser as described by commit bd2fccac61b4 ("drm/dp_mst: Fix MST sideband message body length check"). Fix the above by resetting the message reception state if needed before reading/parsing a message. Another solution would be to hold the drm_dp_mst_topology_mgr::lock for the whole duration of the message reception/parsing in drm_dp_mst_handle_down_rep() and drm_dp_mst_handle_up_req(), however this would require a bigger change. Since the fix is also needed for stable, opting for the simpler solution in this patch. Cc: Lyude Paul <lyude@redhat.com> Cc: <stable@vger.kernel.org> Fixes: 1d082618bbf3 ("drm/display/dp_mst: Fix down/up message handling after sink disconnect") Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13056 Signed-off-by: Imre Deak <imre.deak@intel.com> --- drivers/gpu/drm/display/drm_dp_mst_topology.c | 21 +++++++++++++++++-- include/drm/display/drm_dp_mst_helper.h | 7 +++++++ 2 files changed, 26 insertions(+), 2 deletions(-)