native runtime: implement memory bounds check

runtimes/native/src/runtime.c

@@ -1,6 +1,7 @@
 #include "runtime.h"
 
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include "apu.h"
@@ -40,6 +41,51 @@ static Memory* memory;
 static w4_Disk* disk;
 static bool firstFrame;
 
+static void panic(const char *msg)
+{
+    /* REVISIT: it's cleaner to raise a wasm trap */
+    fprintf(stderr, "fatal error in host function: %s\n", msg);
+    exit(1);
+}
+
+static void out_of_bounds_access(void)
+{
+    panic("out of bands memory access");
+}
+
+static uint32_t mul_u32_with_overflow_check(uint32_t a, uint32_t b)
+{
+    uint32_t c = a * b;
+    if (c / a != b) {
+        panic("integer overflow");
+    }
+    return c;
+}
+
+static void bounds_check(const void *sp, size_t sz)
+{
+    const void *memory_sp = (const void *)memory;
+    const void *memory_ep = (const uint8_t *)memory_sp + (1 << 16);
+    const void *ep = (const uint8_t *)sp + sz;
+    if (ep < sp || sp < memory_sp || memory_ep < ep) {
+        out_of_bounds_access();
+    }
+}
+
+static void bounds_check_cstr(const char *p)
+{
+    const void *memory_sp = (const void *)memory;
+    const void *memory_ep = (const uint8_t *)memory_sp + (1 << 16);
+    if (p < memory_sp || memory_ep <= p) {
+        out_of_bounds_access();
+    }
+    while (*p++ != 0) {
+        if (memory_ep <= p) {
+            out_of_bounds_access();
+        }
+    }
+}
+
 void w4_runtimeInit (uint8_t* memoryBytes, w4_Disk* diskBytes) {
     memory = (Memory*)memoryBytes;
     disk = diskBytes;
@@ -83,6 +129,9 @@ void w4_runtimeBlitSub (const uint8_t* sprite, int x, int y, int width, int heig
     bool flipX = (flags & 2);
     bool flipY = (flags & 4);
     bool rotate = (flags & 8);
+    uint32_t bpp = (int)bpp2 + 1;
+    uint32_t nbits = mul_u32_with_overflow_check(mul_u32_with_overflow_check(width, height), bpp);
+    bounds_check(sprite, nbits / 8);
     w4_framebufferBlit(sprite, x, y, width, height, srcX, srcY, stride, bpp2, flipX, flipY, rotate);
 }
 
@@ -112,16 +161,19 @@ void w4_runtimeRect (int x, int y, int width, int height) {
 }
 
 void w4_runtimeText (const uint8_t* str, int x, int y) {
+    bounds_check_cstr(str);
     // printf("text: %s, %d, %d\n", str, x, y);
     w4_framebufferText(str, x, y);
 }
 
 void w4_runtimeTextUtf8 (const uint8_t* str, int byteLength, int x, int y) {
+    bounds_check(str, byteLength);
     // printf("textUtf8: %p, %d, %d, %d\n", str, byteLength, x, y);
     w4_framebufferTextUtf8(str, byteLength, x, y);
 }
 
 void w4_runtimeTextUtf16 (const uint16_t* str, int byteLength, int x, int y) {
+    bounds_check(str, byteLength);
     // printf("textUtf16: %p, %d, %d, %d\n", str, byteLength, x, y);
     w4_framebufferTextUtf16(str, byteLength, x, y);
 }
@@ -132,6 +184,7 @@ void w4_runtimeTone (int frequency, int duration, int volume, int flags) {
 }
 
 int w4_runtimeDiskr (uint8_t* dest, int size) {
+    bounds_check(dest, size);
     if (!disk) {
         return 0;
     }
@@ -144,6 +197,7 @@ int w4_runtimeDiskr (uint8_t* dest, int size) {
 }
 
 int w4_runtimeDiskw (const uint8_t* src, int size) {
+    bounds_check(src, size);
     if (!disk) {
         return 0;
     }
@@ -157,20 +211,24 @@ int w4_runtimeDiskw (const uint8_t* src, int size) {
 }
 
 void w4_runtimeTrace (const uint8_t* str) {
+    bounds_check_cstr(str);
     puts(str);
 }
 
 void w4_runtimeTraceUtf8 (const uint8_t* str, int byteLength) {
+    bounds_check(str, byteLength);
     printf("%.*s\n", byteLength, str);
 }
 
 void w4_runtimeTraceUtf16 (const uint16_t* str, int byteLength) {
+    bounds_check(str, byteLength);
     printf("TODO: traceUtf16: %p, %d\n", str, byteLength);
 }
 
 void w4_runtimeTracef (const uint8_t* str, const void* stack) {
     const uint8_t* argPtr = stack;
     uint32_t strPtr;
+    bounds_check_cstr(str);
     for (; *str != 0; ++str) {
         if (*str == '%') {
             const uint8_t sym = *(++str);
@@ -181,27 +239,30 @@ void w4_runtimeTracef (const uint8_t* str, const void* stack) {
                 putc('%', stdout);
                 break;
             case 'c':
+                bounds_check(argPtr, 4);
                 putc(*(char*)argPtr, stdout);
                 argPtr += 4;
                 break;
             case 'd':
+                bounds_check(argPtr, 4);
                 printf("%d", *(int32_t*)argPtr);
                 argPtr += 4;
                 break;
             case 'x':
+                bounds_check(argPtr, 4);
                 printf("%x", *(uint32_t*)argPtr);
                 argPtr += 4;
                 break;
             case 's':
+                bounds_check(argPtr, 4);
                 strPtr = *(uint32_t*)argPtr;
                 argPtr += 4;
-                if (strPtr > 0 && strPtr < sizeof(*memory)) {
-                    printf("%.*s", (int)(sizeof(*memory) - strPtr), (char*)memory + strPtr);
-                } else {
-                    printf("<invalid memory>");
-                }
+                const char *strPtr_host = (const char *)memory + strPtr;
+                bounds_check_cstr(strPtr_host);
+                printf("%s", strPtr_host);
                 break;
             case 'f':
+                bounds_check(argPtr, 8);
                 printf("%lg", *(double*)argPtr);
                 argPtr += 8;
                 break;

test/integer_overflow/blit_1bpp_overflow.wat

@@ -0,0 +1,13 @@
+(module
+  (func $blit (import "env" "blit") (param i32 i32 i32 i32 i32 i32))
+  (memory (import "env" "memory") 1 1)
+  (func (export "update")
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0x10
+    i32.const 0x10000001
+    i32.const 0
+    call $blit
+  )
+)

test/integer_overflow/blit_2bpp_overflow.wat

@@ -0,0 +1,13 @@
+(module
+  (func $blit (import "env" "blit") (param i32 i32 i32 i32 i32 i32))
+  (memory (import "env" "memory") 1 1)
+  (func (export "update")
+    i32.const 0
+    i32.const 0
+    i32.const 0
+    i32.const 0x8
+    i32.const 0x10000001
+    i32.const 1
+    call $blit
+  )
+)

test/out_of_bands_memory_access/blit_1bpp.wat

@@ -0,0 +1,13 @@
+(module
+  (func $blit (import "env" "blit") (param i32 i32 i32 i32 i32 i32))
+  (memory (import "env" "memory") 1 1)
+  (func (export "update")
+    i32.const 65529
+    i32.const 0
+    i32.const 0
+    i32.const 8
+    i32.const 8
+    i32.const 0
+    call $blit
+  )
+)

test/out_of_bands_memory_access/blit_2bpp.wat

@@ -0,0 +1,13 @@
+(module
+  (func $blit (import "env" "blit") (param i32 i32 i32 i32 i32 i32))
+  (memory (import "env" "memory") 1 1)
+  (func (export "update")
+    i32.const 65521
+    i32.const 0
+    i32.const 0
+    i32.const 8
+    i32.const 8
+    i32.const 1
+    call $blit
+  )
+)

test/out_of_bands_memory_access/tracef_double.wat

@@ -0,0 +1,10 @@
+(module
+  (func $tracef (import "env" "tracef") (param i32 i32))
+  (memory (import "env" "memory") 1 1)
+  (func (export "update")
+    i32.const 50000
+    i32.const 65529
+    call $tracef
+  )
+  (data (i32.const 50000) "%f\00")
+)

test/out_of_bands_memory_access/tracef_fmt.wat

@@ -0,0 +1,10 @@
+(module
+  (func $tracef (import "env" "tracef") (param i32 i32))
+  (memory (import "env" "memory") 1 1)
+  (func (export "update")
+    i32.const 65533
+    i32.const 0
+    call $tracef
+  )
+  (data (i32.const 65533) "xxx")
+)

test/out_of_bands_memory_access/tracef_str.wat

@@ -0,0 +1,15 @@
+(module
+  (func $tracef (import "env" "tracef") (param i32 i32))
+  (memory (import "env" "memory") 1 1)
+  (func (export "update")
+    i32.const 40000
+    i32.const 65533
+    i32.store
+
+    i32.const 50000
+    i32.const 40000
+    call $tracef
+  )
+  (data (i32.const 50000) "%s\00")
+  (data (i32.const 65533) "xxx")
+)

test/out_of_bands_memory_access/tracef_strptr.wat

@@ -0,0 +1,10 @@
+(module
+  (func $tracef (import "env" "tracef") (param i32 i32))
+  (memory (import "env" "memory") 1 1)
+  (func (export "update")
+    i32.const 50000
+    i32.const 65533
+    call $tracef
+  )
+  (data (i32.const 50000) "%s\00")
+)