From e2aa5b2ace432d24be067044a333128514b46faf Mon Sep 17 00:00:00 2001
From: Francis Ricci <francisjricci@gmail.com>
Date: Mon, 2 Oct 2017 14:30:58 +0000
Subject: [PATCH] Add support for custom loaders to the sanitizer symbolizer

Summary:
Adds a fallback mode to procmaps when the symbolizer
fails to locate a module for a given address by using
dl_iterate_phdr.

Reviewers: kubamracek, rnk, vitalybuka, eugenis

Reviewed By: eugenis

Subscribers: srhines, llvm-commits

Differential Revision: https://reviews.llvm.org/D37269

llvm-svn: 314671
---
 compiler-rt/lib/sanitizer_common/sanitizer_common.h           |  1 +
 compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cc   | 11 +++++++++++
 compiler-rt/lib/sanitizer_common/sanitizer_mac.cc             |  2 ++
 compiler-rt/lib/sanitizer_common/sanitizer_symbolizer.h       |  1 +
 .../lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc      |  5 +++++
 compiler-rt/lib/sanitizer_common/sanitizer_win.cc             |  4 +++-
 6 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common.h b/compiler-rt/lib/sanitizer_common/sanitizer_common.h
index 11ee590..ee5eca5 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common.h
@@ -730,6 +730,7 @@ class ListOfModules {
   ListOfModules() : initialized(false) {}
   ~ListOfModules() { clear(); }
   void init();
+  void fallbackInit();  // Uses fallback init if available, otherwise clears
   const LoadedModule *begin() const { return modules_.begin(); }
   LoadedModule *begin() { return modules_.begin(); }
   const LoadedModule *end() const { return modules_.end(); }
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cc b/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cc
index 0f42087..c25b561 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cc
@@ -488,6 +488,17 @@ void ListOfModules::init() {
   }
 }
 
+// When a custom loader is used, dl_iterate_phdr may not contain the full
+// list of modules. Allow callers to fall back to using procmaps.
+void ListOfModules::fallbackInit() {
+  if (!requiresProcmaps()) {
+    clearOrInit();
+    procmapsInit(&modules_);
+  } else {
+    clear();
+  }
+}
+
 // getrusage does not give us the current RSS, only the max RSS.
 // Still, this is better than nothing if /proc/self/statm is not available
 // for some reason, e.g. due to a sandbox.
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cc b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cc
index cd63cb4..9fead91 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cc
@@ -416,6 +416,8 @@ void ListOfModules::init() {
   memory_mapping.DumpListOfModules(&modules_);
 }
 
+void ListOfModules::fallbackInit() { clear(); }
+
 static HandleSignalMode GetHandleSignalModeImpl(int signum) {
   switch (signum) {
     case SIGABRT:
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer.h b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer.h
index 9558712..208362d 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer.h
@@ -152,6 +152,7 @@ class Symbolizer final {
                                          uptr *module_offset,
                                          ModuleArch *module_arch);
   ListOfModules modules_;
+  ListOfModules fallback_modules_;
   // If stale, need to reload the modules before looking up addresses.
   bool modules_fresh_;
 
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc
index 37ac12c..a4bab66 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_symbolizer_libcdep.cc
@@ -165,6 +165,7 @@ bool Symbolizer::FindModuleNameAndOffsetForAddress(uptr address,
 
 void Symbolizer::RefreshModules() {
   modules_.init();
+  fallback_modules_.fallbackInit();
   RAW_CHECK(modules_.size() > 0);
   modules_fresh_ = true;
 }
@@ -198,6 +199,10 @@ const LoadedModule *Symbolizer::FindModuleForAddress(uptr address) {
     if (module) return module;
   }
 #endif
+
+  if (fallback_modules_.size()) {
+    module = SearchForModule(fallback_modules_, address);
+  }
   return module;
 }
 
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_win.cc b/compiler-rt/lib/sanitizer_common/sanitizer_win.cc
index 84065aa..f1a74d3 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_win.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_win.cc
@@ -583,7 +583,9 @@ void ListOfModules::init() {
     modules_.push_back(cur_module);
   }
   UnmapOrDie(hmodules, modules_buffer_size);
-};
+}
+
+void ListOfModules::fallbackInit() { clear(); }
 
 // We can't use atexit() directly at __asan_init time as the CRT is not fully
 // initialized at this point.  Place the functions into a vector and use
-- 
2.7.4