Merge pull request #1690 from bettio/fix-boxed-int-imm-bug

Fix potential memory corruption with boxed immediate integers

These changes are made under both the "Apache 2.0" and the "GNU Lesser General
Public License 2.1 or later" license terms (dual license).

SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later

Author: bettio

CHANGELOG.md

@@ -68,6 +68,8 @@ memory error
 - Fixed `erlang:is_number/1` function, now returns true also for floats
 - Fixed unlink protocol and add support for `link/1` on ports
 - Do not abort when an out of memory happens while loading a literal value
+- Fixed potential memory corruption when handling integer immediates that are stored as boxed
+integer (this never happens with integers < 28 bits)
 
 ### Changed
 

src/libAtomVM/opcodesswitch.h

@@ -1531,21 +1531,27 @@ static term maybe_alloc_boxed_integer_fragment(Context *ctx, avm_int64_t value)
 {
 #if BOXED_TERMS_REQUIRED_FOR_INT64 > 1
     if ((value < AVM_INT_MIN) || (value > AVM_INT_MAX)) {
-        if (UNLIKELY(memory_ensure_free_opt(ctx, BOXED_INT64_SIZE, MEMORY_NO_GC) != MEMORY_GC_OK)) {
+        Heap heap;
+        if (UNLIKELY(memory_init_heap(&heap, BOXED_INT64_SIZE) != MEMORY_GC_OK)) {
             ctx->x[0] = ERROR_ATOM;
             ctx->x[1] = OUT_OF_MEMORY_ATOM;
             return term_invalid_term();
         }
-        return term_make_boxed_int64(value, &ctx->heap);
+        memory_heap_append_heap(&ctx->heap, &heap);
+
+        return term_make_boxed_int64(value, &heap);
     } else
 #endif
     if ((value < MIN_NOT_BOXED_INT) || (value > MAX_NOT_BOXED_INT)) {
-        if (UNLIKELY(memory_ensure_free_opt(ctx, BOXED_INT_SIZE, MEMORY_NO_GC) != MEMORY_GC_OK)) {
+        Heap heap;
+        if (UNLIKELY(memory_init_heap(&heap, BOXED_INT_SIZE) != MEMORY_GC_OK)) {
             ctx->x[0] = ERROR_ATOM;
             ctx->x[1] = OUT_OF_MEMORY_ATOM;
             return term_invalid_term();
         }
-        return term_make_boxed_int(value, &ctx->heap);
+        memory_heap_append_heap(&ctx->heap, &heap);
+
+        return term_make_boxed_int(value, &heap);
     } else {
         return term_from_int(value);
     }