[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, 2 insertions, 1 deletions

diff --git a/address_translator.h b/address_translator.h
index 821b9ad..5666b99 100644
--- a/address_translator.h
+++ b/address_translator.h
@@ -59,7 +59,7 @@ namespace zucchini {
 using rva_t = uint32_t;
 // Divide by 2 to match |kOffsetBound|.
 constexpr rva_t kRvaBound = static_cast<rva_t>(-1) / 2;
-constexpr rva_t kInvalidRva = static_cast<rva_t>(-1);
+constexpr rva_t kInvalidRva = static_cast<rva_t>(-2);
 
 // A utility to translate between offsets and RVAs in an image.
 class AddressTranslator {
@@ -133,6 +133,7 @@ class AddressTranslator {
     explicit RvaToOffsetCache(const AddressTranslator& translator);
 
     bool IsValid(rva_t rva) const;
+
     offset_t Convert(rva_t rva) const;
 
    private: