fix(audio): bound audio-heap cache tables (SIGSEGV with large custom music packs) (#6932)

Root cause of three identical field crashes (audio thread, opcode fetch
through a pointer with its low 32 bits overwritten, seconds after scene
transitions): AudioHeap_AllocPermanent writes permanentCache[index] with
index = permanentPool.count and no bound against the 32-entry array. In
SoH every soundfont sync-load is forced permanent, and custom sequences
whose SEQ.xml says CachePolicy="Temporary" ALSO allocate permanently
(the factory stores the LUS enum where CACHE_TEMPORARY == 0, while
AudioLoad_SyncLoad's switch reads 0 with the ROM convention
'permanent'). A pack with ~60 streamed customs plus vanilla fonts pushes
count past 32 within a session, after which each allocation sprays a
{ptr, size, tableType/id} triplet at 24-byte stride through
gAudioContext - entry[135]'s ptr field lands exactly on
seqPlayers[0].scriptState.pc and entry[156] on seqPlayers[1]'s (both
verified against the crash-dump registers).

- permanentCache raised 32 -> 512 (12 KB) and AllocPermanent refuses
  allocations past the array instead of corrupting memory.
- Same unbounded-index disease fixed in the three sibling writers:
  AllocCached's persistent path (16-entry array; CACHE_EITHER degrades
  to temporary, hard persistent requests fail cleanly),
  AllocPersistentSampleCacheEntry, AllocTemporarySampleCacheEntry.
- seqLoadStatus malloc sized for the full id space (sequenceMapSize +
  0xF) matching sequenceMap; custom ids above sequenceMapSize previously
  overflowed the allocation by up to 15 bytes.

Upstream SoH bugs, not branch-introduced - this branch's many-track
packs merely made the overflow reachable in normal play. Standalone
upstreamable fix.

3 files changed, 27 insertions, 3 deletions

diff --git a/soh/include/z64audio.h b/soh/include/z64audio.h
index 42328cd8e..6fed61399 100644
--- a/soh/include/z64audio.h
+++ b/soh/include/z64audio.h
@@ -915,7 +915,8 @@ typedef struct {
     /* 0x2B30 */ AudioCache fontCache;
     /* 0x2C40 */ AudioCache sampleBankCache;
     /* 0x2D50 */ AudioAllocPool permanentPool;
-    /* 0x2D60 */ AudioCacheEntry permanentCache[32];
+    // SOH [Bugfix] 32 -> 512: large custom-music packs overflowed this (see AudioHeap_AllocPermanent).
+    /* 0x2D60 */ AudioCacheEntry permanentCache[512];
     /* 0x2EE0 */ AudioSampleCache persistentSampleCache;
     /* 0x3174 */ AudioSampleCache temporarySampleCache;
     /* 0x3408 */ AudioPoolSplit4 sessionPoolSplit;
diff --git a/soh/src/code/audio_heap.c b/soh/src/code/audio_heap.c
index 398946fa9..a6f2dae1e 100644
--- a/soh/src/code/audio_heap.c
+++ b/soh/src/code/audio_heap.c
@@ -534,6 +534,14 @@ void* AudioHeap_AllocCached(s32 tableType, ptrdiff_t size, s32 cache, s32 id) {
         return ret;
     }
 
+    // SOH [Bugfix] Bound entries[] (see AudioHeap_AllocPermanent); CACHE_EITHER falls back to temporary.
+    if (loadedPool->persistent.numEntries >= ARRAY_COUNT(loadedPool->persistent.entries)) {
+        if (cache == CACHE_EITHER) {
+            return AudioHeap_AllocCached(tableType, size, CACHE_TEMPORARY, id);
+        }
+        return NULL;
+    }
+
     mem = AudioHeap_Alloc(&loadedPool->persistent.pool, size);
     loadedPool->persistent.entries[loadedPool->persistent.numEntries].ptr = mem;
 
@@ -1011,6 +1019,12 @@ void* AudioHeap_AllocPermanent(s32 tableType, s32 id, size_t size) {
 
     index = gAudioContext.permanentPool.count;
 
+    // SOH [Bugfix] Bound permanentCache: large custom-music packs overflowed it and corrupted
+    // gAudioContext (crashed the audio thread). Refuse rather than corrupt memory; callers handle NULL.
+    if (index >= ARRAY_COUNT(gAudioContext.permanentCache)) {
+        return NULL;
+    }
+
     ret = AudioHeap_Alloc(&gAudioContext.permanentPool, size);
     gAudioContext.permanentCache[index].ptr = ret;
     if (ret == NULL) {
@@ -1134,6 +1148,10 @@ SampleCacheEntry* AudioHeap_AllocTemporarySampleCacheEntry(size_t size) {
     }
 
     if (index == -1) {
+        // SOH [Bugfix] Bound entries[] (see AudioHeap_AllocPermanent); callers treat NULL as uncached.
+        if (pool->size >= ARRAY_COUNT(pool->entries)) {
+            return NULL;
+        }
         index = pool->size++;
     }
 
@@ -1210,6 +1228,10 @@ SampleCacheEntry* AudioHeap_AllocPersistentSampleCacheEntry(size_t size) {
     void* mem;
 
     pool = &gAudioContext.persistentSampleCache;
+    // SOH [Bugfix] Bound entries[] (see AudioHeap_AllocPermanent).
+    if (pool->size >= ARRAY_COUNT(pool->entries)) {
+        return NULL;
+    }
     mem = AudioHeap_Alloc(&pool->pool, size);
     if (mem == NULL) {
         return NULL;
diff --git a/soh/src/code/audio_load.c b/soh/src/code/audio_load.c
index 582cf3a1c..fcebb7104 100644
--- a/soh/src/code/audio_load.c
+++ b/soh/src/code/audio_load.c
@@ -1350,8 +1350,9 @@ void AudioLoad_Init(void* heap, size_t heapSize) {
     // calloc: unassigned slots stay NULL for the guard in AudioLoad_SyncInitSeqPlayerInternal().
     sequenceMap = calloc(sequenceMapSize + 0xF, sizeof(char*));
 
-    gAudioContext.seqLoadStatus = malloc(sequenceMapSize);
-    memset(gAudioContext.seqLoadStatus, 5, sequenceMapSize);
+    // SOH [Bugfix] Size to match sequenceMap (+ 0xF); custom ids can exceed sequenceMapSize.
+    gAudioContext.seqLoadStatus = malloc(sequenceMapSize + 0xF);
+    memset(gAudioContext.seqLoadStatus, 5, sequenceMapSize + 0xF);
     for (size_t i = 0; i < seqListSize; i++) {
         SequenceData sDat = ResourceMgr_LoadSeqByName(seqList[i]);
         sequenceMap[sDat.seqNumber] = strdup(seqList[i]);