Commit 5497e9e7 authored by Gabriele Svelto's avatar Gabriele Svelto
Browse files

Bug 1878428 - Prevent a deadlock while doing in-process minidump generation r=spohl a=RyanVM 

This removes all the memory allocations which we were doing while writing a
minidump of the crashed process from within the process itself. Under these
conditions all threads are stopped save for the minidump writer; so if another
thread owns a mutex guarding the memory allocator we could deadlock by doing
allocations.

This patch avoids allocating strings entirely and uses Breakpad's alternative
allocator to sidestep the issue where we cannot avoid allocations.

Differential Revision: https://phabricator.services.mozilla.com/D201960
parent 50646242

toolkit/crashreporter/breakpad-client/mac/handler/minidump_generator.cc

+9 −6
Original line number Diff line number Diff line
@@ -83,7 +83,7 @@ MinidumpGenerator::MinidumpGenerator() 
      cpu_type_(DynamicImages::GetNativeCPUType()),

      dyldImageLoadAddress_(NULL),

      dyldSlide_(0),

      dyldPath_(),

      dyldPath_(nullptr),

      task_context_(NULL),

      dynamic_images_(NULL),

      memory_blocks_(&allocator_) {
@@ -105,7 +105,7 @@ MinidumpGenerator::MinidumpGenerator(mach_port_t crashing_task, 
      cpu_type_(DynamicImages::GetNativeCPUType()),

      dyldImageLoadAddress_(NULL),

      dyldSlide_(0),

      dyldPath_(),

      dyldPath_(nullptr),

      task_context_(NULL),

      dynamic_images_(NULL),

      memory_blocks_(&allocator_) {
@@ -250,7 +250,7 @@ void MinidumpGenerator::GatherCurrentProcessDyldInformation() { 
    return;

  }

  dyldImageLoadAddress_ = mh;

  dyldPath_ = string(aii->dyldPath);

  dyldPath_ = aii->dyldPath;

  dyldSlide_ = GetCurrentProcessModuleSlide(mh, aii->sharedCacheSlide);

}
@@ -1464,7 +1464,7 @@ bool MinidumpGenerator::WriteModuleStream(unsigned int index, 
    if (index == INT_MAX) {

      dyld_or_in_dyld_shared_cache = true;

      slide = dyldSlide_;

      name = dyldPath_.c_str();

      name = dyldPath_;

    } else {

      dyld_or_in_dyld_shared_cache =

        ((header->flags & MH_SHAREDCACHE) != 0);
@@ -1993,7 +1993,7 @@ bool MinidumpGenerator::WriteCrashInfoStream( 
      bool dyld_or_in_dyld_shared_cache;

      if (i == image_count - 1) {

        slide = dyldSlide_;

        module_path = dyldPath_.c_str();

        module_path = dyldPath_;

        dyld_or_in_dyld_shared_cache = true;

      } else {

        slide = _dyld_get_image_vmaddr_slide(i);
@@ -2048,7 +2048,10 @@ bool MinidumpGenerator::WriteBootargsStream( 
  int rv = sysctlbyname("kern.bootargs", NULL, &size, NULL, 0);

  if ((rv != 0) || (size == 0))

    size = 1;

  vector<uint8_t> bootargs(size);



  wasteful_vector<uint8_t> bootargs(&this->allocator_, size);

  bootargs.resize(size, 0);



  bootargs[0] = 0;

  if (rv == 0)

    sysctlbyname("kern.bootargs", &bootargs[0], &size, NULL, 0);

toolkit/crashreporter/breakpad-client/mac/handler/minidump_generator.h

+2 −1
Original line number Diff line number Diff line
@@ -266,7 +266,8 @@ class MinidumpGenerator { 
  // process has crashed.

  breakpad_mach_header* dyldImageLoadAddress_;

  ptrdiff_t dyldSlide_;

  string dyldPath_;

  // We don't own this pointer, this is owned by macOS internal structures.

  const char* dyldPath_;



  // Context of the task to dump.

  breakpad_ucontext_t *task_context_;