nx2: ignore syncpoint signals past the syncpoint table

The 3D engine's sync method and the puller's fence action take a
syncpoint id from the command list and signal it, but the syncpoint
manager has 192 syncpoints and does not check the index. Command words
read wrong (Splatoon Raiders on Linux runs 3D engine commands as puller
methods 0x10-0x3F just before) made Maxwell3D signal a syncpoint past
the table: SyncpointManager::Increment walked memory after its action
lists as a list and crashed on a null link (SIGSEGV reading 0x10).
Builds 49 and 50 both crashed this way under WSL. FenceManager now drops
such signals with an error, for every engine that signals.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/video_core/fence_manager.h b/src/video_core/fence_manager.h
index 61c9844cf2..d9f0ac2837 100644
--- a/src/video_core/fence_manager.h
+++ b/src/video_core/fence_manager.h
@@ -18,6 +18,7 @@
 #include <queue>
 
 #include "common/common_types.h"
+#include "common/logging.h"
 #include "common/settings.h"
 #include "common/thread.h"
 #include "video_core/delayed_destruction_ring.h"
@@ -123,6 +124,13 @@ public:
     }
 
     void SignalSyncPoint(u32 value) {
+        // The id comes from a command list (the 3D engine's sync method, the puller's fence
+        // action). Past the syncpoint table, the increment would walk memory after it as an
+        // action list; command words read wrong carry any id (Splatoon Raiders on Linux).
+        if (value >= Tegra::Host1x::SyncpointManager::NUM_MAX_SYNCPOINTS) {
+            LOG_ERROR(HW_GPU, "Signal of syncpoint {} past the table, ignored", value);
+            return;
+        }
         syncpoint_manager.IncrementGuest(value);
         std::function<void()> func([this, value] { syncpoint_manager.IncrementHost(value); });
         SignalFence(std::move(func));