sceIo: Validate PGD block sizes and dir listing state

The PGD block size comes from the file header (or a savestate), and is
used to size the block buffer and as a divisor and mask, so require a sane
power of two. On load, force the next read to fill the buffer, which isn't
saved. sceIoDread only checks the listing index against the end.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

Core/HLE/sceIo.cpp

@@ -275,7 +275,19 @@ public:
 			if (pgdInfo)
 				p.DoVoid(pgdInfo, sizeof(PGD_DESC));
 			if (p.mode == p.MODE_READ && pgdInfo) {
-				pgdInfo->block_buf = (u8 *)malloc(pgdInfo->block_size * 2);
+				pgdInfo->block_buf = nullptr;
+				if (pgd_valid_block_size(pgdInfo->block_size)) {
+					pgdInfo->block_buf = (u8 *)malloc(pgdInfo->block_size * 2);
+				}
+				if (!pgdInfo->block_buf) {
+					ERROR_LOG(Log::sceIo, "Savestate has an invalid PGD block size");
+					p.SetError(p.ERROR_FAILURE);
+					pgd_close(pgdInfo);
+					pgdInfo = nullptr;
+					return;
+				}
+				// The buffer isn't saved, so make the next read fill it.
+				pgdInfo->current_block = -1;
 			}
 		}
 
@@ -2510,6 +2522,13 @@ public:
 		// TODO: Is this the right way for it to wake up?
 		int count = (int) listing.size();
 		Do(p, count);
+		// sceIoDread only checks for index == count.
+		if (count < 0 || index < 0 || index > count || !p.CheckRead(count)) {
+			ERROR_LOG(Log::sceIo, "Savestate has an invalid dir listing");
+			p.SetError(p.ERROR_FAILURE);
+			index = 0;
+			return;
+		}
 		listing.resize(count);
 		for (int i = 0; i < count; ++i) {
 			listing[i].DoState(p);

ext/libkirk/amctrl.c

@@ -678,6 +678,11 @@ PGD_DESC *pgd_open(KirkState *kirk, u8 *pgd_buf, int pgd_flag, u8 *pgd_vkey)
 	pgd->data_offset = *(u32*)(pgd_buf+0x4c);
 	memcpy(pgd->dkey, pgd_buf+0x30, 16);
 
+	if(!pgd_valid_block_size(pgd->block_size)){
+		free(pgd);
+		return NULL;
+	}
+
 	pgd->align_size = (pgd->data_size+15)&~15;
 	pgd->table_offset = pgd->data_offset+pgd->align_size;
 	pgd->block_nr = (pgd->align_size+pgd->block_size-1)&~(pgd->block_size-1);
@@ -686,6 +691,10 @@ PGD_DESC *pgd_open(KirkState *kirk, u8 *pgd_buf, int pgd_flag, u8 *pgd_vkey)
 	pgd->file_offset = 0;
 	pgd->current_block = -1;
 	pgd->block_buf = (u8*)malloc(pgd->block_size*2);
+	if(pgd->block_buf==NULL){
+		free(pgd);
+		return NULL;
+	}
 
 	return pgd;
 }

ext/libkirk/amctrl.h

@@ -41,6 +41,11 @@ typedef struct {
 	u32 file_offset;
 }PGD_DESC;
 
+// block_size comes from the file (or a savestate). Reads mask with block_size - 1, so it must be a power of two.
+static inline int pgd_valid_block_size(u32 block_size) {
+	return block_size >= 16 && block_size <= 0x100000 && (block_size & (block_size - 1)) == 0;
+}
+
 
 // type:
 //      2: use fuse id