Fix EXECUTE/?/DUMP/TYPE/DECIMAL-HEX-OCTAL/ALIGN defects from proof sweep

proof/FINDINGS.md's Isabelle/HOL word-source sweep (§4) flagged five real
defects; this fixes all five and records resolution in that doc:

- EXECUTE (system_words.c): cast a popped cell straight to a DictEntry*
  and called through it with only a null check. Now validates via a new
  shared vm_dict_entry_ok(), promoted out of starforth_words.c's
  ENTROPY@/ENTROPY! guard (dictionary_management.c) so EXECUTE gets the
  same live-entry check.

- ? and DUMP (format_words.c): dereferenced the popped cell as a raw host
  pointer, bypassing vm_addr_ok entirely (out-of-VM-bounds read). Both now
  go through VM_ADDR/vm_addr_ok/vm_load_cell/vm_ptr like every other
  memory word (@, `,`, editor_words.c).

- TYPE (io_words.c): bounds check computed addr+count in signed 64-bit
  arithmetic, which can overflow and bypass the check on large operands.
  Replaced with vm_addr_ok(), which is written to avoid that overflow.

- DECIMAL/HEX/OCTAL (format_words.c): wrote only the BASE memory cell,
  never vm->base, the host-mirror field number-output words actually read
  via current_base() -- so these words silently affected number parsing
  but never printing. Now call the existing vm_set_base() (previously
  only used at boot init), which updates both. vm_get_base/vm_set_base
  promoted to public declarations in include/vm.h.

- ALIGN vs ALLOT/,/C,/2, (dictionary_words.c): disagreed on dictionary
  growth ceiling (2MB vs 5MB). Investigated which was correct rather than
  blindly widening: vm_get_block_addr() maps block N to
  vm->memory + N*BLOCK_SIZE across the full 5MB arena, and
  USER_BLOCKS_START (block 2048) lines up exactly with
  DICTIONARY_MEMORY_SIZE -- so ALLOT/,/C,/2, letting `here` grow past 2MB
  could silently corrupt live block/user data sharing that memory.
  Tightened ALLOT/,/C,/2, to DICTIONARY_MEMORY_SIZE to match ALIGN.

Verified: hosted (amd64) and kernel (amd64, __STARKERNEL__) both build
clean with -Wall -Werror; hosted POST suite 1012/1012 passing (0
regressions); manually exercised EXECUTE, ?/DUMP, TYPE, HEX/DECIMAL/OCTAL,
and large-ALLOT rejection in the REPL.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014Qf6YcnHgaEtEygq3knx19

src/dictionary_management.c

@@ -157,6 +157,23 @@ DictEntry *vm_dictionary_lookup_by_word_id(VM *vm, uint32_t word_id) {
     return vm->word_id_map[word_id];
 }
 
+int vm_dict_entry_ok(VM *vm, DictEntry *candidate) {
+    if (!vm || !candidate) {
+        return 0;
+    }
+
+    int found = 0;
+    sf_mutex_lock(&vm->dict_lock);
+    for (DictEntry *e = vm->latest; e != NULL; e = e->link) {
+        if (e == candidate) {
+            found = 1;
+            break;
+        }
+    }
+    sf_mutex_unlock(&vm->dict_lock);
+    return found;
+}
+
 /* --- helpers ------------------------------------------------------------- */
 
 static inline void *sf_xrealloc(void *p, size_t nbytes) {

src/memory_management.c

@@ -56,7 +56,7 @@ void *vm_allot(VM *vm, size_t bytes) {
         return NULL;
     }
 
-    /* Ensure we don't allocate beyond dictionary space (first 1024 blocks = 1MB) */
+    /* Ensure we don't allocate beyond dictionary space (first DICTIONARY_BLOCKS blocks = DICTIONARY_MEMORY_SIZE bytes) */
     log_message(LOG_DEBUG, "vm_allot: Requesting %zu bytes, current here=%zu, limit=%d",
                 bytes, vm->here, DICTIONARY_MEMORY_SIZE);
 

src/word_source/dictionary_words.c

@@ -71,7 +71,11 @@ void dictionary_word_allot(VM *vm) {
     }
     cell_t n = vm_pop(vm);
     cell_t new_here = vm->here + n;
-    if (new_here < 0 || new_here > (cell_t) VM_MEMORY_SIZE) {
+    /* Dictionary growth is bounded to DICTIONARY_MEMORY_SIZE, not the full
+     * VM_MEMORY_SIZE: blocks >= USER_BLOCKS_START live in the same flat
+     * vm->memory array (see vm_get_block_addr), so letting `here` grow past
+     * the dictionary region would silently corrupt live block/user data. */
+    if (new_here < 0 || new_here > (cell_t) DICTIONARY_MEMORY_SIZE) {
         vm->error = 1;
         return;
     }
@@ -90,7 +94,7 @@ void dictionary_word_comma(VM *vm) {
     }
     cell_t n = vm_pop(vm);
     vm_align(vm);
-    if (vm->here + (cell_t) sizeof(cell_t) > VM_MEMORY_SIZE) {
+    if (vm->here + (cell_t) sizeof(cell_t) > DICTIONARY_MEMORY_SIZE) {
         vm->error = 1;
         return;
     }
@@ -114,7 +118,7 @@ void dictionary_word_c_comma(VM *vm) {
         return;
     }
     cell_t c = vm_pop(vm);
-    if (vm->here + 1 > VM_MEMORY_SIZE) {
+    if (vm->here + 1 > DICTIONARY_MEMORY_SIZE) {
         vm->error = 1;
         return;
     }
@@ -140,7 +144,7 @@ void dictionary_word_2comma(VM *vm) {
     cell_t high = vm_pop(vm);
     cell_t low = vm_pop(vm);
     vm_align(vm);
-    if (vm->here + (cell_t)(2 * sizeof(cell_t)) > VM_MEMORY_SIZE) {
+    if (vm->here + (cell_t)(2 * sizeof(cell_t)) > DICTIONARY_MEMORY_SIZE) {
         vm->error = 1;
         return;
     }

src/word_source/format_words.c

@@ -157,19 +157,19 @@ void format_word_base(VM *vm) {
 /* DECIMAL ( -- ) — set BASE=10 */
 void format_word_decimal(VM *vm) {
     if (!vm) { return; }
-    vm_store_cell(vm, vm->base_addr, (cell_t) 10);
+    vm_set_base(vm, 10);
 }
 
 /* HEX ( -- ) — set BASE=16 */
 void format_word_hex(VM *vm) {
     if (!vm) { return; }
-    vm_store_cell(vm, vm->base_addr, (cell_t) 16);
+    vm_set_base(vm, 16);
 }
 
 /* OCTAL ( -- ) — set BASE=8 */
 void format_word_octal(VM *vm) {
     if (!vm) { return; }
-    vm_store_cell(vm, vm->base_addr, (cell_t) 8);
+    vm_set_base(vm, 8);
 }
 
 /* <# ( -- ) */
@@ -399,13 +399,12 @@ void format_word_question(VM *vm) {
         vm->error = 1;
         return;
     }
-    cell_t addr = vm_pop(vm);
-    cell_t *ptr = (cell_t *) (uintptr_t) addr;
-    if (!ptr) {
+    vaddr_t addr = VM_ADDR(vm_pop(vm));
+    if (!vm_addr_ok(vm, addr, sizeof(cell_t))) {
         vm->error = 1;
         return;
     }
-    print_number_formatted(vm, *ptr, 0, 0);
+    print_number_formatted(vm, vm_load_cell(vm, addr), 0, 0);
     putchar(' ');
 }
 
@@ -416,21 +415,21 @@ void format_word_dump(VM *vm) {
         return;
     }
     cell_t u = vm_pop(vm);
-    cell_t addr = vm_pop(vm);
+    vaddr_t addr = VM_ADDR(vm_pop(vm));
     if (u < 0) {
         vm->error = 1;
         return;
     }
-    uint8_t *ptr = (uint8_t *) (uintptr_t) addr;
-    if (!ptr) {
+    size_t n = (size_t) u;
+    if (!vm_addr_ok(vm, addr, n)) {
         vm->error = 1;
         return;
     }
-    size_t n = (size_t) u;
-    int addr_width = (int) (sizeof(uintptr_t) * 2);
+    const uint8_t *ptr = vm_ptr(vm, addr);
+    int addr_width = (int) (sizeof(vaddr_t) * 2);
 
     for (size_t i = 0; i < n; i += 16) {
-        unsigned long long a = (unsigned long long) ((uintptr_t) addr + (uintptr_t) i);
+        unsigned long long a = (unsigned long long) (addr + i);
         printf("%0*llX: ", addr_width, a);
         size_t j = 0;
         for (; j < 16 && i + j < n; j++) printf("%02X ", ptr[i + j]);

src/word_source/io_words.c

@@ -122,22 +122,26 @@ static void io_word_type(VM *vm) {
     }
 
     cell_t count = vm_pop(vm);
-    cell_t addr = vm_pop(vm);
+    vaddr_t addr = VM_ADDR(vm_pop(vm));
 
-    // Add bounds checking
-    if (addr < 0 || count < 0 || (addr + count) > VM_MEMORY_SIZE) {
-        log_message(LOG_ERROR, "TYPE: Invalid range [%ld, %ld)", (long) addr, (long) (addr + count));
+    // Bounds check via vm_addr_ok (avoids the addr+count overflow a manual
+    // sum would risk for large signed operands)
+    if (count < 0 || !vm_addr_ok(vm, addr, (size_t) count)) {
+        log_message(LOG_ERROR, "TYPE: Invalid range [addr=%llu, count=%ld)",
+                    (unsigned long long) addr, (long) count);
         vm->error = 1;
         return;
     }
 
     // Output characters from VM memory
+    const uint8_t *src = vm_ptr(vm, addr);
     for (cell_t i = 0; i < count; i++) {
-        putchar(vm->memory[addr + i]);
+        putchar(src[i]);
     }
     fflush(stdout);
 
-    log_message(LOG_DEBUG, "TYPE: Output %ld characters from address %ld", (long) count, (long) addr);
+    log_message(LOG_DEBUG, "TYPE: Output %ld characters from address %llu",
+                (long) count, (unsigned long long) addr);
 }
 
 /**

src/word_source/starforth_words.c

@@ -78,27 +78,6 @@ static uint64_t g_prng_state = 1;
  * Note: Exposed as ENTROPY@ for FORTH compatibility, but measures execution heat.
  * @param vm Pointer to the VM instance
  */
-/**
- * @brief Validate that an address is a valid DictEntry pointer
- * @param vm The VM instance
- * @param candidate The address to validate
- * @return 1 if valid, 0 if not
- */
-static int is_valid_dict_entry(VM* vm, DictEntry* candidate)
-{
-    if (!candidate) return 0;
-
-    /* Walk dictionary to verify this is a real entry - must hold dict_lock */
-    int found = 0;
-    sf_mutex_lock(&vm->dict_lock);
-    for (DictEntry* e = vm->latest; e != NULL; e = e->link)
-    {
-        if (e == candidate) { found = 1; break; }
-    }
-    sf_mutex_unlock(&vm->dict_lock);
-    return found;
-}
-
 void starforth_word_execution_heat_fetch(VM* vm)
 {
     if (vm->dsp < 0)
@@ -119,7 +98,7 @@ void starforth_word_execution_heat_fetch(VM* vm)
     }
 
     /* Guardrail: Validate the pointer is actually a DictEntry */
-    if (!is_valid_dict_entry(vm, entry))
+    if (!vm_dict_entry_ok(vm, entry))
     {
         vm->error = 1;
         log_message(LOG_ERROR, "ENTROPY@: invalid dictionary entry address %p (not in dictionary)", (void*)entry);
@@ -158,7 +137,7 @@ void starforth_word_execution_heat_store(VM* vm)
     }
 
     /* Guardrail: Validate the pointer is actually a DictEntry */
-    if (!is_valid_dict_entry(vm, entry))
+    if (!vm_dict_entry_ok(vm, entry))
     {
         vm->error = 1;
         log_message(LOG_ERROR, "ENTROPY!: invalid dictionary entry address %p (not in dictionary)", (void*)entry);

src/word_source/system_words.c

@@ -569,7 +569,7 @@ static void system_word_execute(VM *vm) {
     if (vm->dsp < 0) { vm->error = 1; return; }
     cell_t xt = vm_pop(vm);
     DictEntry *entry = (DictEntry *)(uintptr_t)xt;
-    if (!entry || !entry->func) { vm->error = 1; return; }
+    if (!vm_dict_entry_ok(vm, entry) || !entry->func) { vm->error = 1; return; }
     vm->current_executing_entry = entry;
     entry->func(vm);
 }