From 8e77c078d68ebd25d70f92f70a5aa630b19c7ee2 Mon Sep 17 00:00:00 2001
From: "thestig@chromium.org"
 <thestig@chromium.org@4c0a9323-5329-0410-9bdc-e9ce6186880e>
Date: Thu, 26 Aug 2010 21:38:51 +0000
Subject: [PATCH] Limit the number of frames we try to walk to prevent runaway
 processors. Review URL: http://breakpad.appspot.com/175001

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@672 4c0a9323-5329-0410-9bdc-e9ce6186880e
---
 src/google_breakpad/processor/stackwalker.h | 8 +++++++-
 src/processor/stackwalker.cc                | 7 ++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/google_breakpad/processor/stackwalker.h b/src/google_breakpad/processor/stackwalker.h
index 3abcee75..36d721d1 100644
--- a/src/google_breakpad/processor/stackwalker.h
+++ b/src/google_breakpad/processor/stackwalker.h
@@ -48,7 +48,6 @@
 namespace google_breakpad {
 
 class CallStack;
-class CodeModule;
 class CodeModules;
 class MemoryRegion;
 class MinidumpContext;
@@ -80,6 +79,9 @@ class Stackwalker {
                                         SymbolSupplier *supplier,
                                         SourceLineResolverInterface *resolver);
 
+  static void set_max_frames(u_int32_t max_frames) { max_frames_ = max_frames; }
+  static u_int32_t max_frames() { return max_frames_; }
+
  protected:
   // system_info identifies the operating system, NULL or empty if unknown.
   // memory identifies a MemoryRegion that provides the stack memory
@@ -146,6 +148,10 @@ class Stackwalker {
   // this in order to avoid repeatedly looking them up again within
   // one minidump.
   set<std::string> no_symbol_modules_;
+
+  // The maximum number of frames Stackwalker will walk through.
+  // This defaults to 1024 to prevent infinite loops.
+  static u_int32_t max_frames_;
 };
 
 
diff --git a/src/processor/stackwalker.cc b/src/processor/stackwalker.cc
index 8552e2f3..39eb65ec 100644
--- a/src/processor/stackwalker.cc
+++ b/src/processor/stackwalker.cc
@@ -55,6 +55,7 @@
 
 namespace google_breakpad {
 
+u_int32_t Stackwalker::max_frames_ = 1024;
 
 Stackwalker::Stackwalker(const SystemInfo *system_info,
                          MemoryRegion *memory,
@@ -120,6 +121,10 @@ bool Stackwalker::Walk(CallStack *stack) {
     // Add the frame to the call stack.  Relinquish the ownership claim
     // over the frame, because the stack now owns it.
     stack->frames_.push_back(frame.release());
+    if (stack->frames_.size() > max_frames_) {
+      BPLOG(ERROR) << "The stack is over " << max_frames_ << " frames.";
+      break;
+    }
 
     // Get the next frame and take ownership.
     frame.reset(GetCallerFrame(stack));
@@ -166,7 +171,7 @@ Stackwalker* Stackwalker::StackwalkerForCPU(
                                              memory, modules, supplier,
                                              resolver);
       break;
-  
+
     case MD_CONTEXT_SPARC:
       cpu_stackwalker = new StackwalkerSPARC(system_info,
                                              context->GetContextSPARC(),