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
4 files changed