Utilize C99 flexible array members to allow for FORTIFY/ASAN

Author: satur9nine

.github/workflows/compilation_on_android_ubuntu.yml

@@ -369,6 +369,48 @@ jobs:
           ctest --output-on-failure
         working-directory: tests/unit
 
+  build_array_bounds_warning_check:
+    needs: [build_llvm_libraries_on_ubuntu_2204]
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-22.04]
+        include:
+          - os: ubuntu-22.04
+            llvm_cache_key: ${{ needs.build_llvm_libraries_on_ubuntu_2204.outputs.cache_key }}
+    steps:
+      - name: checkout
+        uses: actions/checkout@v6.0.2
+        with:
+          submodules: recursive
+
+      - name: Get LLVM libraries
+        id: retrieve_llvm_libs
+        uses: actions/cache@v5
+        with:
+          path: |
+            ./core/deps/llvm/build/bin
+            ./core/deps/llvm/build/include
+            ./core/deps/llvm/build/lib
+            ./core/deps/llvm/build/libexec
+            ./core/deps/llvm/build/share
+          key: ${{ matrix.llvm_cache_key }}
+
+      - name: Quit if cache miss
+        if: steps.retrieve_llvm_libs.outputs.cache-hit != 'true'
+        run: echo "::error::can not get prebuilt llvm libraries" && exit 1
+
+      - name: Build shared-utils with array-bounds warnings as errors
+        run: |
+          mkdir build && cd build
+          cmake .. \
+            -DCMAKE_C_COMPILER=clang \
+            -DCMAKE_CXX_COMPILER=clang++ \
+            -DCMAKE_C_FLAGS="-Werror=array-bounds" \
+            -DCMAKE_CXX_FLAGS="-Werror=array-bounds"
+          cmake --build . --target shared_utils_test --parallel 4
+        working-directory: tests/unit
+
   build_regression_tests:
     needs: [build_llvm_libraries_on_ubuntu_2204]
     runs-on: ${{ matrix.os }}

core/iwasm/aot/aot_runtime.h

@@ -432,7 +432,7 @@ typedef struct AOTFrame {
      *      currently local's ref flags are stored in AOTModule,
      *      here we only reserve the padding bytes
      */
-    uint32 lp[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(uint32, lp);
 } AOTFrame;
 
 #if WASM_ENABLE_STATIC_PGO != 0

core/iwasm/common/gc/gc_object.h

@@ -77,7 +77,7 @@ typedef uintptr_t WASMI31ObjectRef;
 typedef struct WASMStructObject {
     /* Must be pointer of WASMRttObject of struct type */
     WASMObjectHeader header;
-    uint8 field_data[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(uint8, field_data);
 } WASMStructObject, *WASMStructObjectRef;
 
 /* Representation of WASM array objects */
@@ -89,7 +89,7 @@ typedef struct WASMArrayObject {
      * elem_size = 2 ^ (length & 0x3)
      */
     uint32 length;
-    uint8 elem_data[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(uint8, elem_data);
 } WASMArrayObject, *WASMArrayObjectRef;
 
 #define WASM_ARRAY_LENGTH_SHIFT 2

core/iwasm/compilation/aot.h

@@ -133,7 +133,7 @@ typedef struct AOTTableInitData {
     /* Function index count */
     uint32 value_count;
     /* Function index array */
-    InitializerExpression init_values[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(InitializerExpression, init_values);
 } AOTTableInitData;
 
 /**

core/iwasm/interpreter/wasm.h

@@ -270,13 +270,13 @@ typedef union WASMValue {
 typedef struct WASMStructNewInitValues {
     uint32 type_idx;
     uint32 count;
-    WASMValue fields[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(WASMValue, fields);
 } WASMStructNewInitValues;
 
 typedef struct WASMArrayNewInitValues {
     uint32 type_idx;
     uint32 length;
-    WASMValue elem_data[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(WASMValue, elem_data);
 } WASMArrayNewInitValues;
 
 typedef struct InitializerExpression {
@@ -444,7 +444,7 @@ typedef struct WASMFuncType {
     /* types of params and results, only store the first byte
      * of the type, if it cannot be described with one byte,
      * then the full type info is stored in ref_type_maps */
-    uint8 types[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(uint8, types);
 } WASMFuncType;
 
 #if WASM_ENABLE_GC != 0
@@ -486,7 +486,7 @@ typedef struct WASMStructType {
      * the first byte of the field type, if it cannot be described
      * with one byte, then the full field type info is stored in
      * ref_type_maps */
-    WASMStructFieldType fields[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(WASMStructFieldType, fields);
 } WASMStructType;
 
 typedef struct WASMArrayType {
@@ -862,7 +862,7 @@ typedef struct BrTableCache {
     /* Address of br_table opcode */
     uint8 *br_table_op_addr;
     uint32 br_count;
-    uint32 br_depths[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(uint32, br_depths);
 } BrTableCache;
 
 #if WASM_ENABLE_DEBUG_INTERP != 0

core/iwasm/interpreter/wasm_interp.h

@@ -50,7 +50,7 @@ typedef struct WASMInterpFrame {
 #if WASM_ENABLE_GC != 0
     uint8 *frame_ref;
 #endif
-    uint32 operand[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(uint32, operand);
 #else  /* else of WASM_ENABLE_FAST_INTERP != 0 */
     /* Operand stack top pointer of the current frame. The bottom of
        the stack is the next cell after the last local variable. */
@@ -71,7 +71,7 @@ typedef struct WASMInterpFrame {
      *    whether each cell in local and stack area is a GC obj
      *  jit spill cache: only available for fast jit
      */
-    uint32 lp[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(uint32, lp);
 #endif /* end of WASM_ENABLE_FAST_INTERP != 0 */
 } WASMInterpFrame;
 

core/iwasm/interpreter/wasm_runtime.h

@@ -188,7 +188,7 @@ struct WASMTableInstance {
     /* Maximum size */
     uint32 max_size;
     /* Table elements */
-    table_elem_type_t elems[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(table_elem_type_t, elems);
 };
 
 struct WASMGlobalInstance {

core/shared/platform/include/platform_common.h

@@ -99,6 +99,16 @@ BH_VPRINTF(const char *format, va_list ap);
 #endif
 #endif
 
+/* Prefer C99 flexible array members for FORTIFY/ASAN compatibility */
+#ifndef BH_FLEXIBLE_ARRAY_MEMBER
+#if !defined(__cplusplus) && defined(__STDC_VERSION__) \
+    && __STDC_VERSION__ >= 199901L
+#define BH_FLEXIBLE_ARRAY_MEMBER(type, name) type name[]
+#else
+#define BH_FLEXIBLE_ARRAY_MEMBER(type, name) type name[1]
+#endif
+#endif
+
 typedef uint8_t uint8;
 typedef int8_t int8;
 typedef uint16_t uint16;

core/shared/utils/bh_bitmap.h

@@ -23,7 +23,7 @@ typedef struct bh_bitmap {
     uintptr_t end_index;
 
     /* The bitmap.  */
-    uint8 map[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(uint8, map);
 } bh_bitmap;
 
 /**

core/shared/utils/bh_hashmap.c

@@ -22,7 +22,7 @@ struct HashMap {
     KeyEqualFunc key_equal_func;
     KeyDestroyFunc key_destroy_func;
     ValueDestroyFunc value_destroy_func;
-    HashMapElem *elements[1];
+    BH_FLEXIBLE_ARRAY_MEMBER(HashMapElem *, elements);
 };
 
 HashMap *