ELF modules are loaded in memory in several, possibly discontiguous,
segments. If the holes between segments are large enough, other things,
possibly other ELF modules may be mapped in that space. Crashpad
records the range of modules as the base address of the lowest mapped
segment to the high address of the highest mapped segment. This means
that when one module is mapped into a hole in another, it appears to
the Breakpad processor as overlapping modules. Module ranges are
relevant to the Breakpad processor during stackwalking for identifying
which module a particular program counter belongs to (i.e. mapping the
address to a module's text segment). This patch addresses this issue of
overlapping modules by truncating the range of the module with the
lower base address. A typical module's text segment is the first loaded
segment which would leave the text segment range unaffected. Module
producers can restrict the size of holes in their ELF modules with the
flag "-Wl,-z,max-page-size=4096", preventing other modules from being
mapped in their address range.
Properly contemplating ELF module address ranges would require
extensions to the minidump format to encode any holes.
crbug.com/crashpad/298
This patch also renames the concept of "shrinking down" (which
truncated the upper of two overlapping ranges) to "truncate upper".
Change-Id: I4599201f1e43918db036c390961f8b39e3af1849
Reviewed-on: https://chromium-review.googlesource.com/c/breakpad/breakpad/+/1646932
Reviewed-by: Mark Mentovai <mark@chromium.org>
This change is resolving an issue that was caused by the combination of:
- Android system libraries being relro packed in N+.
- Breakpad dealing with relro packed libraries in a hack way.
This is a fix for http://crbug/611824.
I also found an use-after-free issue (bug in Minidump::SeekToStreamType). I disallowed the MinidumpStreamInfo copy and assign constructors and the compiler detected another similar issue in Minidump::Print. Then I disabled the copy and assign constructors for most classes in minidump.h (just in case). There are a couple of classes where I couldn't disallow them (since assign is used). This will require a small refactor so I left it out of this CL.
R=mark@chromium.org
Review URL: https://codereview.chromium.org/2060663002 .
When enabled, adding of a new range that overlaps with an existing one can be a successful operation. The range which ends at the higher address will be shrunk down by moving its start position to a higher address so that it does not overlap anymore.
This change is required to fix http://crbug/611824. The actual fix will come in a separate CL.
R=mmandlis@chromium.org
Review URL: https://codereview.chromium.org/2029953003 .
- Introduces a standard API for dealing with modules. MinidumpModule
is now a concrete implementation of this API. Code may interact with
single modules using the CodeModule interface, and collections of
modules using its container, the CodeModules interface.
- CodeModule is used directly by SymbolSupplier implementations and
SourceLineResolver. Reliance on the specific implementation in
MinidumpModule has been eliminated.
- Module lists are now added to ProcessState objects. Module references
in each stack frame are now pointers to objects in these module lists.
- The sample minidump_stackwalk tool prints the module list after printing
all threads' stacks.
http://groups.google.com/group/airbag-dev/browse_frm/thread/a9c0550edde54cf8
git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@74 4c0a9323-5329-0410-9bdc-e9ce6186880e
- Eliminate MemAddrMap from source_line_resolver.cc and adapt it to use
RangeMap, also used by minidump.cc.
- RangeMap operates on both a base address and a size, where MemAddrMap
only used a base address, so the dumped symbol file format is modified
to include size information. dump_syms produces these files and
SourceLineResolver consumes them.
- Provide updated test data conforming to the new dumped symbol format.
http://groups.google.com/group/airbag-dev/browse_thread/thread/e9403cf3ad6336a1
git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@21 4c0a9323-5329-0410-9bdc-e9ce6186880e
- In class definitions, one-space indent for public/protected/private.
- Multi-line initializer format puts comma at end of line.
Also:
- Eliminate the long list of friends in Minidump by making swap() public.
(People who need to access unknown stream types directly will need
access to swap() too.)
git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@16 4c0a9323-5329-0410-9bdc-e9ce6186880e
