Hardened MMU permission checks

src/memory/memory.c

@@ -63,6 +63,13 @@ void mem_write8(uint32_t address, uint8_t value)
 		io = io->next;
 	}
 
+	// Check if we are inside of physical memory
+	if(address + 1 > memory_size)
+	{
+		fprintf(stderr, "MEMORY: Invalid write of size 1 outside of physical memory at address 0x%x\n", address);
+		exit(EXIT_FAILURE);
+	}
+
 	// Proceed with memory write
 	pthread_mutex_lock(&memory_mutex);
 	memory[address] = value;
@@ -94,6 +101,13 @@ void mem_write16(uint32_t address, uint16_t value)
 		io = io->next;
 	}
 
+	// Check if we are inside of physical memory
+	if(address + 2 > memory_size)
+	{
+		fprintf(stderr, "MEMORY: Invalid write of size 2 outside of physical memory at address 0x%x\n", address);
+		exit(EXIT_FAILURE);
+	}
+
 	// Proceed with memory write
 	pthread_mutex_lock(&memory_mutex);
 	*((uint16_t*) &memory[address]) = value;
@@ -125,6 +139,13 @@ void mem_write32(uint32_t address, uint32_t value)
 		io = io->next;
 	}
 
+	// Check if we are inside of physical memory
+	if(address + 4 > memory_size)
+	{
+		fprintf(stderr, "MEMORY: Invalid write of size 1 outside of physical memory at address 0x%x\n", address);
+		exit(EXIT_FAILURE);
+	}
+
 	// Proceed with memory write
 	pthread_mutex_lock(&memory_mutex);
 	*((uint32_t*) &memory[address]) = value;
@@ -155,6 +176,13 @@ uint8_t mem_read8(uint32_t address)
 		io = io->next;
 	}
 
+	// Check if we are inside of physical memory
+	if(address + 1 > memory_size)
+	{
+		fprintf(stderr, "MEMORY: Invalid read of size 1 outside of physical memory at address 0x%x\n", address);
+		exit(EXIT_FAILURE);
+	}
+
 	// Proceed with memory read
 	pthread_mutex_lock(&memory_mutex);
 	uint8_t tr = memory[address];
@@ -186,6 +214,13 @@ uint16_t mem_read16(uint32_t address)
 		io = io->next;
 	}
 
+	// Check if we are inside of physical memory
+	if(address + 2 > memory_size)
+	{
+		fprintf(stderr, "MEMORY: Invalid read of size 2 outside of physical memory at address 0x%x\n", address);
+		exit(EXIT_FAILURE);
+	}
+
 	// Proceed with memory read
 	pthread_mutex_lock(&memory_mutex);
 	uint16_t tr = *((uint16_t*) &memory[address]);
@@ -217,6 +252,13 @@ uint32_t mem_read32(uint32_t address)
 		io = io->next;
 	}
 
+	// Check if we are inside of physical memory
+	if(address + 4 > memory_size)
+	{
+		fprintf(stderr, "MEMORY: Invalid read of size 4 outside of physical memory at address 0x%x\n", address);
+		exit(EXIT_FAILURE);
+	}
+
 	// Proceed with memory read
 	pthread_mutex_lock(&memory_mutex);
 	uint32_t tr = *((uint32_t*) &memory[address]);
@@ -240,6 +282,13 @@ uint32_t mem_fetch(uint32_t address)
 		io = io->next;
 	}
 
+	// Check if we are inside of physical memory
+	if(address + 4 > memory_size)
+	{
+		fprintf(stderr, "MEMORY: Invalid fetch outside of physical memory at address 0x%x\n", address);
+		exit(EXIT_FAILURE);
+	}
+
 	// Proceed with memory read
 	pthread_mutex_lock(&memory_mutex);
 	uint32_t tr = *((uint32_t*) &memory[address]);

src/memory/mmu.c

@@ -89,6 +89,18 @@ uint32_t mmu_resolve(rv32_cpu_t* cpu, memory_access_type_t access_type, uint32_t
 		// Leaf PTE, we are ready to resolve the mapping
 		// This is a 4 MiB megapage
 
+		// For an execute, check if we are allowed to execute
+		if(access_type == INSTRUCTION_FETCH && !(pte & PTE_X))
+			exception_trigger(cpu, mmu_scause_from_access(access_type), vaddr);
+
+		// For a write, check if we are allowed to write
+		if(access_type == WRITE && !(pte & PTE_W))
+			exception_trigger(cpu, mmu_scause_from_access(access_type), vaddr);
+
+		// For a read, check if we are allowed to read
+		if(access_type == READ && !(pte & PTE_R))
+			exception_trigger(cpu, mmu_scause_from_access(access_type), vaddr);
+
 		// Physical Address: [PPN[1] = pte.PPN[1], PPN[0] = vaddr.VPN[0], offset]
 		uint32_t paddr = 0;
 		paddr |= (PTE_PPN_1(pte) << 22);
@@ -120,6 +132,18 @@ uint32_t mmu_resolve(rv32_cpu_t* cpu, memory_access_type_t access_type, uint32_t
 		exit(EXIT_FAILURE);
 	}
 
+	// For an execute, check if we are allowed to execute
+	if(access_type == INSTRUCTION_FETCH && !(pte & PTE_X))
+		exception_trigger(cpu, mmu_scause_from_access(access_type), vaddr);
+
+	// For a write, check if we are allowed to write
+	if(access_type == WRITE && !(pte & PTE_W))
+		exception_trigger(cpu, mmu_scause_from_access(access_type), vaddr);
+
+	// For a read, check if we are allowed to read
+	if(access_type == READ && !(pte & PTE_R))
+		exception_trigger(cpu, mmu_scause_from_access(access_type), vaddr);
+
 	// Physical Address: [PPN[1] = pte.PPN[1], PPN[0] = pte.PPN[0], offset]
 	uint32_t paddr = 0;
 	paddr |= (PTE_PPN_1(pte) << 22);