Print real size in heap command #1748 (#1781)

* Updated heap command to show real size without flag bits

* Fixed linters

* Fixed linters

* Fixed real size

* Fixed heap tests

* Fixed linters

pwndbg/commands/heap.py

@@ -422,7 +422,7 @@ def malloc_chunk(addr, fake=False, verbose=False, simple=False) -> None:
     if verbose:
         fields_to_print.update(["prev_size", "size", "fd", "bk", "fd_nextsize", "bk_nextsize"])
     else:
-        out_fields += f"Size: 0x{chunk.size:02x}\n"
+        out_fields += f"Size: 0x{chunk.real_size:02x} (with flag bits: 0x{chunk.size:02x})\n"
 
     prev_inuse, is_mmapped, non_main_arena = allocator.chunk_flags(chunk.size)
     if prev_inuse:
@@ -434,7 +434,14 @@ def malloc_chunk(addr, fake=False, verbose=False, simple=False) -> None:
 
     fields_ordered = ["prev_size", "size", "fd", "bk", "fd_nextsize", "bk_nextsize"]
     for field_to_print in fields_ordered:
-        if field_to_print in fields_to_print:
+        if field_to_print not in fields_to_print:
+            continue
+        if field_to_print == "size":
+            out_fields += (
+                message.system("size")
+                + f": 0x{chunk.real_size:02x} (with flag bits: 0x{chunk.size:02x})\n"
+            )
+        else:
             out_fields += (
                 message.system(field_to_print) + f": 0x{getattr(chunk, field_to_print):02x}\n"
             )

tests/gdb-tests/tests/heap/test_find_fake_fast.py

@@ -68,10 +68,10 @@ def test_find_fake_fast_command(start_binary):
 
     # setup_mem(0x2F, 0x8)
     result = gdb.execute("find_fake_fast &target_address", to_string=True)
-    check_result(result, 0x2F)
+    check_result(result, 0x28)
 
     result = gdb.execute("find_fake_fast --align &target_address", to_string=True)
-    check_result(result, 0x2F)
+    check_result(result, 0x28)
     gdb.execute("continue")
 
     # setup_mem(0x20, 0x9)

tests/gdb-tests/tests/heap/test_heap.py

@@ -14,42 +14,83 @@ HEAP_MALLOC_CHUNK = tests.binaries.get("heap_malloc_chunk.out")
 
 def generate_expected_malloc_chunk_output(chunks):
     expected = {}
+
+    size = int(
+        chunks["allocated"][
+            "mchunk_size"
+            if "mchunk_size" in (f.name for f in chunks["allocated"].type.fields())
+            else "size"
+        ]
+    )
+    real_size = size & (0xFFFFFFFFFFFFFFF - 0b111)
     expected["allocated"] = [
         "Allocated chunk | PREV_INUSE",
         f"Addr: {chunks['allocated'].address}",
-        f"Size: 0x{int(chunks['allocated']['mchunk_size' if 'mchunk_size' in (f.name for f in chunks['allocated'].type.fields()) else 'size']):02x}",
+        f"Size: 0x{real_size:02x} (with flag bits: 0x{size:02x})",
         "",
     ]
 
+    size = int(
+        chunks["tcache"][
+            "mchunk_size"
+            if "mchunk_size" in (f.name for f in chunks["tcache"].type.fields())
+            else "size"
+        ]
+    )
+    real_size = size & (0xFFFFFFFFFFFFFFF - 0b111)
     expected["tcache"] = [
         f"Free chunk ({'tcachebins' if pwndbg.heap.current.has_tcache else 'fastbins'}) | PREV_INUSE",
         f"Addr: {chunks['tcache'].address}",
-        f"Size: 0x{int(chunks['tcache']['mchunk_size' if 'mchunk_size' in (f.name for f in chunks['tcache'].type.fields()) else 'size']):02x}",
+        f"Size: 0x{real_size:02x} (with flag bits: 0x{size:02x})",
         f"fd: 0x{int(chunks['tcache']['fd']):02x}",
         "",
     ]
 
+    size = int(
+        chunks["fast"][
+            "mchunk_size"
+            if "mchunk_size" in (f.name for f in chunks["fast"].type.fields())
+            else "size"
+        ]
+    )
+    real_size = size & (0xFFFFFFFFFFFFFFF - 0b111)
     expected["fast"] = [
         "Free chunk (fastbins) | PREV_INUSE",
         f"Addr: {chunks['fast'].address}",
-        f"Size: 0x{int(chunks['fast']['mchunk_size' if 'mchunk_size' in (f.name for f in chunks['fast'].type.fields()) else 'size']):02x}",
+        f"Size: 0x{real_size:02x} (with flag bits: 0x{size:02x})",
         f"fd: 0x{int(chunks['fast']['fd']):02x}",
         "",
     ]
 
+    size = int(
+        chunks["small"][
+            "mchunk_size"
+            if "mchunk_size" in (f.name for f in chunks["small"].type.fields())
+            else "size"
+        ]
+    )
+    real_size = size & (0xFFFFFFFFFFFFFFF - 0b111)
     expected["small"] = [
         "Free chunk (smallbins) | PREV_INUSE",
         f"Addr: {chunks['small'].address}",
-        f"Size: 0x{int(chunks['small']['mchunk_size' if 'mchunk_size' in (f.name for f in chunks['small'].type.fields()) else 'size']):02x}",
+        f"Size: 0x{real_size:02x} (with flag bits: 0x{size:02x})",
         f"fd: 0x{int(chunks['small']['fd']):02x}",
         f"bk: 0x{int(chunks['small']['bk']):02x}",
         "",
     ]
 
+    size = int(
+        chunks["large"][
+            "mchunk_size"
+            if "mchunk_size" in (f.name for f in chunks["large"].type.fields())
+            else "size"
+        ]
+    )
+    real_size = size & (0xFFFFFFFFFFFFFFF - 0b111)
     expected["large"] = [
         "Free chunk (largebins) | PREV_INUSE",
         f"Addr: {chunks['large'].address}",
-        f"Size: 0x{int(chunks['large']['mchunk_size' if 'mchunk_size' in (f.name for f in chunks['large'].type.fields()) else 'size']):02x}",
+        f"Size: 0x{real_size:02x} (with flag bits: 0x{size:02x})",
         f"fd: 0x{int(chunks['large']['fd']):02x}",
         f"bk: 0x{int(chunks['large']['bk']):02x}",
         f"fd_nextsize: 0x{int(chunks['large']['fd_nextsize']):02x}",
@@ -57,10 +98,18 @@ def generate_expected_malloc_chunk_output(chunks):
         "",
     ]
 
+    size = int(
+        chunks["unsorted"][
+            "mchunk_size"
+            if "mchunk_size" in (f.name for f in chunks["unsorted"].type.fields())
+            else "size"
+        ]
+    )
+    real_size = size & (0xFFFFFFFFFFFFFFF - 0b111)
     expected["unsorted"] = [
         "Free chunk (unsortedbin) | PREV_INUSE",
         f"Addr: {chunks['unsorted'].address}",
-        f"Size: 0x{int(chunks['unsorted']['mchunk_size' if 'mchunk_size' in (f.name for f in chunks['unsorted'].type.fields()) else 'size']):02x}",
+        f"Size: 0x{real_size:02x} (with flag bits: 0x{size:02x})",
         f"fd: 0x{int(chunks['unsorted']['fd']):02x}",
         f"bk: 0x{int(chunks['unsorted']['bk']):02x}",
         "",