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, 12 insertions, 2 deletions

diff --git a/src/processor/minidump.cc b/src/processor/minidump.cc
index 4ad82053..7ad736d5 100755
--- a/src/processor/minidump.cc
+++ b/src/processor/minidump.cc
@@ -1509,13 +1509,15 @@ bool MinidumpThread::Read() {
   }
 
   // Check for base + size overflow or undersize.
-  if (thread_.stack.memory.data_size == 0 ||
+  if (thread_.stack.memory.rva == 0 ||
+      thread_.stack.memory.data_size == 0 ||
       thread_.stack.memory.data_size > numeric_limits<uint64_t>::max() -
                                        thread_.stack.start_of_memory_range) {
     // This is ok, but log an error anyway.
     BPLOG(ERROR) << "MinidumpThread has a memory region problem, " <<
                     HexString(thread_.stack.start_of_memory_range) << "+" <<
-                    HexString(thread_.stack.memory.data_size);
+                    HexString(thread_.stack.memory.data_size) <<
+                    ", RVA 0x" << HexString(thread_.stack.memory.rva);
   } else {
     memory_ = new MinidumpMemoryRegion(minidump_);
     memory_->SetDescriptor(&thread_.stack);
@@ -1525,6 +1527,14 @@ bool MinidumpThread::Read() {
   return true;
 }
 
+uint64_t MinidumpThread::GetStartOfStackMemoryRange() const {
+  if (!valid_) {
+    BPLOG(ERROR) << "GetStartOfStackMemoryRange: Invalid MinidumpThread";
+    return 0;
+  }
+
+  return thread_.stack.start_of_memory_range;
+}
 
 MinidumpMemoryRegion* MinidumpThread::GetMemory() {
   if (!valid_) {