This change is addressing a particularly nasty issue where the stackwalker

doesn't see the correct thread stack memory.  Instead, it loads garbage
(from offset 0 of the minidump file - well that's not garbage, but it is
not the stack memory region either) and attempts to walk it.  A typical
symptom of this issue is when you get a single stack frame after
processing - the context frame - for which you don't need stack memory.

This issue is caused by an invalid RVA in the memory descriptor stored
inside the MINIDUMP_THREAD structure for the thread.  Luckily, the
invalid RVA is 0, and the start_of_memory_region appears to be correct,
so this issue can be easily detected and the correct memory region can be
loaded using an RVA specified in the MinidumpMemoryList.

I couldn't find a reasonable description on MSDN regarding
MINIDUMP_MEMORY_DESCRIPTOR.MINIDUMP_LOCATION_DESCRIPTOR having RVA of 0
except maybe for full dumps where the 64-bit version of the structure
(MINIDUMP_MEMORY_DESCRIPTOR64) is used and it has no RVA at all.  It has
a 64-bit DataSize which if interpreted as the 32-bit structure will very
likely result in 0 for the RVA:
  http://msdn.microsoft.com/en-us/library/windows/desktop/ms680384(v=vs.85).aspx 

Anyways, the dump that I looked at was not a full dump so 0 for RVA is a
bit puzzling (at least easily detectable):
...
Microsoft (R) Windows Debugger Version 6.2.9200.20512 X86
Copyright (c) Microsoft Corporation. All rights reserved.
...
User Mini Dump File: Only registers, stack and portions of memory are available
...
MINIDUMP_HEADER:
Version         A793 (62F0)
NumberOfStreams 11
Flags           160
                0020 MiniDumpWithUnloadedModules
                0040 MiniDumpWithIndirectlyReferencedMemory
                0100 MiniDumpWithProcessThreadData
Review URL: https://breakpad.appspot.com/606002

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1194 4c0a9323-5329-0410-9bdc-e9ce6186880e

1 files changed, 8 insertions, 2 deletions

diff --git a/src/google_breakpad/processor/minidump.h b/src/google_breakpad/processor/minidump.h
index 8b2d0fe8..16b9d856 100644
--- a/src/google_breakpad/processor/minidump.h
+++ b/src/google_breakpad/processor/minidump.h
@@ -326,6 +326,11 @@ class MinidumpThread : public MinidumpObject {
   // Print a human-readable representation of the object to stdout.
   void Print();
 
+  // Returns the start address of the thread stack memory region.  Returns 0 if
+  // MinidumpThread is invalid.  Note that this method can be called even when
+  // the thread memory cannot be read and GetMemory returns NULL.
+  virtual uint64_t GetStartOfStackMemoryRange() const;
+
  protected:
   explicit MinidumpThread(Minidump* minidump);
 
@@ -586,13 +591,14 @@ class MinidumpMemoryList : public MinidumpStream {
 
   // Random access to memory regions.  Returns the region encompassing
   // the address identified by address.
-  MinidumpMemoryRegion* GetMemoryRegionForAddress(uint64_t address);
+  virtual MinidumpMemoryRegion* GetMemoryRegionForAddress(uint64_t address);
 
   // Print a human-readable representation of the object to stdout.
   void Print();
 
  private:
   friend class Minidump;
+  friend class MockMinidumpMemoryList;
 
   typedef vector<MDMemoryDescriptor>   MemoryDescriptors;
   typedef vector<MinidumpMemoryRegion> MemoryRegions;
@@ -932,7 +938,7 @@ class Minidump {
   // parameter).
   virtual MinidumpThreadList* GetThreadList();
   MinidumpModuleList* GetModuleList();
-  MinidumpMemoryList* GetMemoryList();
+  virtual MinidumpMemoryList* GetMemoryList();
   MinidumpException* GetException();
   MinidumpAssertion* GetAssertion();
   virtual MinidumpSystemInfo* GetSystemInfo();