Add regression test for find_fake_fast command

[CptGibbon]

The test program creates a fake chunk size field in its .data section with a set NON_MAIN_ARENA flag.
The Python test runs the find_fake_fast command on an address succeeding the fake chunk.
A gdb.MemoryError indicates regression - issue #1142

[codecov-commenter]

Codecov Report

Merging #1147 (a7a7fe5) into dev (88c6101) will increase coverage by 0.35%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##              dev    #1147      +/-   ##
==========================================
+ Coverage   50.22%   50.57%   +0.35%     
==========================================
  Files         173      173              
  Lines       19866    19874       +8     
  Branches     1814     1814              
==========================================
+ Hits         9978    10052      +74     
+ Misses       9551     9466      -85     
- Partials      337      356      +19     

Impacted Files	Coverage Δ
tests/test_heap.py	95.13% <100.00%> (+0.17%)	⬆️
pwndbg/lib/memory.py	85.52% <0.00%> (+1.31%)	⬆️
pwndbg/heap/ptmalloc.py	38.44% <0.00%> (+1.46%)	⬆️
pwndbg/color/context.py	55.35% <0.00%> (+1.78%)	⬆️
pwndbg/color/message.py	92.30% <0.00%> (+5.12%)	⬆️
pwndbg/commands/heap.py	60.98% <0.00%> (+6.31%)	⬆️
pwndbg/color/memory.py	82.97% <0.00%> (+6.38%)	⬆️

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[disconnect3d]

Confirmed that this test indeed fails with the reverted fix commit:

dc@jhtc:/opt/pwndbg$ git revert 8dae554
[dev 84264c8] Revert "Add gdb.MemoryError check to get_heap() (#1145)"
 1 file changed, 2 insertions(+), 9 deletions(-)
dc@jhtc:/opt/pwndbg$ ./tests.sh test_find_fake_fast_command
ZIGPATH set to /opt/pwndbg/.zig
[+] Cleaning stuff
[+] Building heap_bugs.out
/opt/pwndbg/.zig/zig cc \
-target native-native-gnu.2.33 \
-Wl,-rpath=/opt/pwndbg/tests/binaries/glibcs/2.33:\
/opt/pwndbg/tests/binaries/glibcs/2.33/math:\
/opt/pwndbg/tests/binaries/glibcs/2.33/elf:\
/opt/pwndbg/tests/binaries/glibcs/2.33/dlfcn:\
/opt/pwndbg/tests/binaries/glibcs/2.33/nss:\
/opt/pwndbg/tests/binaries/glibcs/2.33/nis:\
/opt/pwndbg/tests/binaries/glibcs/2.33/rt:\
/opt/pwndbg/tests/binaries/glibcs/2.33/resolv:\
/opt/pwndbg/tests/binaries/glibcs/2.33/crypt:\
/opt/pwndbg/tests/binaries/glibcs/2.33/nptl_db:\
/opt/pwndbg/tests/binaries/glibcs/2.33/nptl:\
-Wl,--dynamic-linker=/opt/pwndbg/tests/binaries/glibcs/2.33/ld-linux-x86-64.so.2 \
-Wall -DDEBUG=1 -ggdb -O0 -gdwarf-4 -o heap_bugs.out heap_bugs.c
[+] Building 'heap_bins.out'
[+] Building 'telescope_binary.out'
[+] Building 'heap_find_fake_fast.out'
[+] Building 'reference-binary.out'
[+] Building 'vmmap.out'
[+] Building heap_vis.out
gcc -g -O0 -Wno-nonnull -o heap_vis.out heap_vis.c -pthread -lpthread
[+] Building 'emulate_disasm.o'
[+] Linking 'emulate_disasm.out'
[+] Building 'memory.o'
[+] Linking 'memory.out'
[+] Building 'emulate_disasm_loop.o'
[+] Linking 'emulate_disasm_loop.out'
[+] Building 'gosample.x86'
[+] Building 'gosample.x64'
rm emulate_disasm_loop.o emulate_disasm.o memory.o
pwndbg: loaded 203 commands. Type pwndbg [filter] for a list.
pwndbg: created $rebase, $ida gdb functions (can be used with print/break)
Launching pytest with args: ['/opt/pwndbg/tests/test_heap.py::test_find_fake_fast_command', '-vvv', '-s', '--showlocals', '--color=yes']
===================================================== test session starts =====================================================
platform linux -- Python 3.6.9, pytest-7.0.1, pluggy-0.13.1 -- /usr/bin/python
cachedir: .pytest_cache
rootdir: /opt/pwndbg
plugins: cov-2.10.0
collecting ... collected 1 item

tests/test_heap.py::test_find_fake_fast_command
Program stopped.
0x00007ffff7dd4090 in _start () from /lib64/ld-linux-x86-64.so.2
Breakpoint 1 at 0x55555555464e: file heap_find_fake_fast.c, line 14.

Breakpoint 1, break_here () at heap_find_fake_fast.c:14
14	void break_here(void) {}
FAKE CHUNKS
Traceback (most recent call last):
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 145, in __call__
    return self.function(*args, **kwargs)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 238, in _OnlyWhenRunning
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 287, in _OnlyWithResolvedHeapSyms
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 263, in _OnlyWhenHeapIsInitialized
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/heap.py", line 318, in malloc_chunk
    arena = allocator.get_arena_for_chunk(cursor)
  File "/opt/pwndbg/pwndbg/heap/ptmalloc.py", line 310, in get_arena_for_chunk
    r = self.get_arena(arena_addr=self.get_heap(addr)["ar_ptr"])
  File "/opt/pwndbg/pwndbg/heap/ptmalloc.py", line 654, in get_arena
    if pwndbg.vmmap.find(arena_addr) is None
  File "/opt/pwndbg/pwndbg/lib/memoize.py", line 50, in __call__
    value = self.func(*args, **kwargs)
  File "/opt/pwndbg/pwndbg/vmmap.py", line 100, in find
    address = int(address)
gdb.MemoryError: Cannot access memory at address 0x555554000000

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 145, in __call__
    return self.function(*args, **kwargs)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 238, in _OnlyWhenRunning
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 287, in _OnlyWithResolvedHeapSyms
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 263, in _OnlyWhenHeapIsInitialized
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/heap.py", line 607, in find_fake_fast
    malloc_chunk(start + offset - psize, fake=True)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 150, in __call__
    pwndbg.exception.handle(self.function.__name__)
  File "/opt/pwndbg/pwndbg/exception.py", line 59, in handle
    raise e
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 145, in __call__
    return self.function(*args, **kwargs)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 238, in _OnlyWhenRunning
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 287, in _OnlyWithResolvedHeapSyms
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 263, in _OnlyWhenHeapIsInitialized
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/heap.py", line 318, in malloc_chunk
    arena = allocator.get_arena_for_chunk(cursor)
  File "/opt/pwndbg/pwndbg/heap/ptmalloc.py", line 310, in get_arena_for_chunk
    r = self.get_arena(arena_addr=self.get_heap(addr)["ar_ptr"])
  File "/opt/pwndbg/pwndbg/heap/ptmalloc.py", line 654, in get_arena
    if pwndbg.vmmap.find(arena_addr) is None
  File "/opt/pwndbg/pwndbg/lib/memoize.py", line 50, in __call__
    value = self.func(*args, **kwargs)
  File "/opt/pwndbg/pwndbg/vmmap.py", line 100, in find
    address = int(address)
gdb.MemoryError: Cannot access memory at address 0x555554000000

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 102, in invoke
    return self(*args, **kwargs)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 150, in __call__
    pwndbg.exception.handle(self.function.__name__)
  File "/opt/pwndbg/pwndbg/exception.py", line 59, in handle
    raise e
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 145, in __call__
    return self.function(*args, **kwargs)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 238, in _OnlyWhenRunning
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 287, in _OnlyWithResolvedHeapSyms
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 263, in _OnlyWhenHeapIsInitialized
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/heap.py", line 607, in find_fake_fast
    malloc_chunk(start + offset - psize, fake=True)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 150, in __call__
    pwndbg.exception.handle(self.function.__name__)
  File "/opt/pwndbg/pwndbg/exception.py", line 59, in handle
    raise e
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 145, in __call__
    return self.function(*args, **kwargs)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 238, in _OnlyWhenRunning
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 287, in _OnlyWithResolvedHeapSyms
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/__init__.py", line 263, in _OnlyWhenHeapIsInitialized
    return function(*a, **kw)
  File "/opt/pwndbg/pwndbg/commands/heap.py", line 318, in malloc_chunk
    arena = allocator.get_arena_for_chunk(cursor)
  File "/opt/pwndbg/pwndbg/heap/ptmalloc.py", line 310, in get_arena_for_chunk
    r = self.get_arena(arena_addr=self.get_heap(addr)["ar_ptr"])
  File "/opt/pwndbg/pwndbg/heap/ptmalloc.py", line 654, in get_arena
    if pwndbg.vmmap.find(arena_addr) is None
  File "/opt/pwndbg/pwndbg/lib/memoize.py", line 50, in __call__
    value = self.func(*args, **kwargs)
  File "/opt/pwndbg/pwndbg/vmmap.py", line 100, in find
    address = int(address)
gdb.MemoryError: Cannot access memory at address 0x555554000000
FAILED

========================================================== FAILURES ===========================================================
_________________________________________________ test_find_fake_fast_command _________________________________________________

start_binary = <function start_binary.<locals>._start_binary at 0x7faae9707950>

    def test_find_fake_fast_command(start_binary):
        start_binary(HEAP_FIND_FAKE_FAST)
        gdb.execute("break break_here")
        gdb.execute("continue")

        # Ensure memory at fake_chunk's heap_info struct isn't mapped.
        unmapped_heap_info = pwndbg.heap.ptmalloc.heap_for_ptr(pwndbg.symbol.address("fake_chunk"))
        assert pwndbg.gdblib.memory.peek(unmapped_heap_info) is None

        # A gdb.MemoryError raised here indicates a regression from PR #1145
>       gdb.execute("find_fake_fast (void*)&fake_chunk+0x70")
E       gdb.error: Error occurred in Python: Cannot access memory at address 0x555554000000

start_binary = <function start_binary.<locals>._start_binary at 0x7faae9707950>
unmapped_heap_info = 93824969867264

tests/test_heap.py:417: error
=================================================== short test summary info ===================================================
FAILED tests/test_heap.py::test_find_fake_fast_command - gdb.error: Error occurred in Python: Cannot access memory at addres...
====================================================== 1 failed in 0.37s ======================================================
--------------------------------------------------------------------------------
If you want to debug tests locally, modify pytests_launcher.py and add --pdb to its args
--------------------------------------------------------------------------------

*********************************
********* TESTS SUMMARY *********
*********************************
Tests passed or skipped: 0
Tests failed: 1
dc@jhtc:/opt/pwndbg$ git ll
* 84264c8 - (HEAD -> dev) Revert "Add gdb.MemoryError check to get_heap() (#1145)" (14 seconds ago) <disconnect3d>
* 88c6101 - (origin/dev, origin/HEAD) fix distance command (#1146) (33 hours ago) <Disconnect3d>
* 8dae554 - Add gdb.MemoryError check to get_heap() (#1145) (34 hours ago) <CptGibbon>
* dea9a69 - add color for modified registers (#1127) (35 hours ago) <syheliel>