[Zucchini] Fix patch apply failure from untranslatable abs32 references.

Disassembler (Win32 and ELF) uses reloc to find abs32 locations, which
are stored in (1) |abs32_locations_|. Later on, (1) is filtered to
generate (2) actual abs32 locations.

A patching failure case was discovered: Equivalence blocks must never
cut across reference boundaries. However, it turns out blocks generated
using (2) were subject to checks using (1), which triggers a failure
since (1) - (2) is nonempty.

One way for (1) != (2) to happen is from CURRENT_MODULE() usage, which
creates an abs32 reference outside a section. This results in an abs32
target whose RVA does not map to an offset using section data, and
gets rejected by filtering logic for (2).

Fix: Apply the filtering logic direcly to (1), so (1) == (2). Details:
* Add RemoveUntranslatableAbs32() (abs32_utils.h), which uses the
  filtering logic for (2) to preemptively remove problematic RVAs
  from (1), so |abs32_locations_| matches (2). Extensive unit tests
  are added.
* DisassemblerWin32<Traits>::ParseAndStoreAbs32(): Initialize
  |abs32_locations_| with 3 steps: Naive extraction from relocs,
  RemoveUntranslatableAbs32(), and RemoveOverlappingAbs32Locations().
* DisassemblerElf<Traits>::GetAbs32FromRelocSections(): Do the same,
  noting that ELF's image base is always 0.

Additional fixes:
* address_translator.h: kInvalidRva was -1, but it should be -2 to
  better match kInvalidOffset.
* Abs32RvaExtractorWin32::Abs32RvaExtractorWin32: The lambda
  |find_and_check| binds |addr|, which has been std::move()'ed.
  Better to just bind |this| and use |addr_|.

Bug: 892284
Change-Id: I628f4668ea231c7e06f35bd924652ca4d74bb848
Reviewed-on: https://chromium-review.googlesource.com/c/1263877
Reviewed-by: Greg Thompson <grt@chromium.org>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Commit-Queue: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#598342}
NOKEYCHECK=True
GitOrigin-RevId: b6d108f1cabab2a9f3fe46a7cdeb92685a2c790e

1 files changed, 14 insertions, 6 deletions

diff --git a/disassembler_win32.cc b/disassembler_win32.cc
index b3f568b..9067ad7 100644
--- a/disassembler_win32.cc
+++ b/disassembler_win32.cc
@@ -316,20 +316,28 @@ bool DisassemblerWin32<Traits>::ParseAndStoreAbs32() {
     return true;
   has_parsed_abs32_ = true;
 
-  ParseAndStoreRelocBlocks();
-
+  // Read reloc targets as preliminary abs32 locations.
   std::unique_ptr<ReferenceReader> relocs = MakeReadRelocs(0, offset_t(size()));
   for (auto ref = relocs->GetNext(); ref.has_value(); ref = relocs->GetNext())
     abs32_locations_.push_back(ref->target);
 
-  abs32_locations_.shrink_to_fit();
   std::sort(abs32_locations_.begin(), abs32_locations_.end());
 
+  // Abs32 references must have targets translatable to offsets. Remove those
+  // that are unable to do so.
+  size_t num_untranslatable = RemoveUntranslatableAbs32(
+      image_, {Traits::kBitness, image_base_}, translator_, &abs32_locations_);
+  LOG_IF(WARNING, num_untranslatable) << "Removed " << num_untranslatable
+                                      << " untranslatable abs32 references.";
+
   // Abs32 reference bodies must not overlap. If found, simply remove them.
-  size_t num_removed =
+  size_t num_overlapping =
       RemoveOverlappingAbs32Locations(Traits::kVAWidth, &abs32_locations_);
-  LOG_IF(WARNING, num_removed) << "Found and removed " << num_removed
-                               << " abs32 locations with overlapping bodies.";
+  LOG_IF(WARNING, num_overlapping)
+      << "Removed " << num_overlapping
+      << " abs32 references with overlapping bodies.";
+
+  abs32_locations_.shrink_to_fit();
   return true;
 }