Write a memory around the instruction pointer from the crashing thread to the minidump on Linux

src/client/linux/handler/exception_handler_unittest.cc

 // Copyright (c) 2010 Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 14 matching lines @@
 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <string>
 
 #include <stdint.h>
 #include <unistd.h>
 #include <signal.h>
+#include <sys/mman.h>
 #include <sys/poll.h>
 #include <sys/socket.h>
 #include <sys/uio.h>
 
 #include "breakpad_googletest_includes.h"
 #include "client/linux/handler/exception_handler.h"
 #include "client/linux/minidump_writer/minidump_writer.h"
 #include "common/linux/eintr_wrapper.h"
 #include "common/linux/linux_libc_support.h"
 #include "third_party/lss/linux_syscall_support.h"
+#include "google_breakpad/processor/minidump.h"
 
 using namespace google_breakpad;
 
 static void sigchld_handler(int signo) { }
 
 class ExceptionHandlerTest : public ::testing::Test {
  protected:
   void SetUp() {
     // We need to be able to wait for children, so SIGCHLD cannot be SIG_IGN.
     struct sigaction sa;
@@ skipping 64 matching lines @@
   filename[len] = 0;
   close(fds[0]);
 
   const std::string minidump_filename = std::string("/tmp/") + filename +
                                         ".dmp";
 
   struct stat st;
   ASSERT_EQ(stat(minidump_filename.c_str(), &st), 0);
   ASSERT_GT(st.st_size, 0u);
   unlink(minidump_filename.c_str());
+}
+
+TEST(ExceptionHandlerTest, InstructionPointerMemory) {
+  int fds[2];
+  ASSERT_NE(pipe(fds), -1);
+
+  const pid_t child = fork();
+  if (child == 0) {
+    close(fds[0]);
+    ExceptionHandler handler("/tmp", NULL, DoneCallback, (void*) fds[1],
+                             true);
+    // Get some executable memory.
+    const size_t memory_size = 256;  // bytes
+    char* memory =
+      reinterpret_cast<char*>(mmap(NULL,
+                                   memory_size,
+                                   PROT_READ | PROT_WRITE | PROT_EXEC,
+                                   MAP_PRIVATE | MAP_ANON,
+                                   -1,
+                                   0));
+    if (!memory)
+      exit(0);
+
+    // Write some instructions that will crash. Put them in the middle
+    // of the block of memory, because the minidump should contain 128
+    // bytes on either side of the instruction pointer.
+    const int offset = memory_size / 2;
+    // This crashes with SIGILL on x86/x86-64/arm.
+    const unsigned char instructions[] = { 0xff, 0xff, 0xff, 0xff };
+    memcpy(memory + offset, instructions, sizeof(instructions));
+    
+    // Now execute the instructions, which should crash.
+    typedef void (*void_function)(void);
+    void_function memory_function =
+      reinterpret_cast<void_function>(memory + offset);
+    memory_function();
+  }
+  close(fds[1]);
+
+  int status;
+  ASSERT_NE(HANDLE_EINTR(waitpid(child, &status, 0)), -1);
+  ASSERT_TRUE(WIFSIGNALED(status));
+  ASSERT_EQ(WTERMSIG(status), SIGILL);
+
+  struct pollfd pfd;
+  memset(&pfd, 0, sizeof(pfd));
+  pfd.fd = fds[0];
+  pfd.events = POLLIN | POLLERR;
+
+  const int r = HANDLE_EINTR(poll(&pfd, 1, 0));
+  ASSERT_EQ(r, 1);
+  ASSERT_TRUE(pfd.revents & POLLIN);
+
+  uint32_t len;
+  ASSERT_EQ(read(fds[0], &len, sizeof(len)), (ssize_t)sizeof(len));
+  ASSERT_LT(len, (uint32_t)2048);
+  char* filename = reinterpret_cast<char*>(malloc(len + 1));
+  ASSERT_EQ(read(fds[0], filename, len), len);
+  filename[len] = 0;
+  close(fds[0]);
+
+  const std::string minidump_filename = std::string("/tmp/") + filename +
+                                        ".dmp";
+
+  struct stat st;
+  ASSERT_EQ(stat(minidump_filename.c_str(), &st), 0);
+  ASSERT_GT(st.st_size, 0u);
+
+  // Read the minidump. Locate the exception record and the
+  // memory list, and then ensure that there is a memory region
+  // in the memory list that covers the instruction pointer from
+  // the exception record.
+  Minidump minidump(minidump_filename);
+  ASSERT_TRUE(minidump.Read());
+
+  MinidumpException* exception = minidump.GetException();
+  MinidumpMemoryList* memory_list = minidump.GetMemoryList();
+  ASSERT_TRUE(exception);
+  ASSERT_TRUE(memory_list);
+  ASSERT_LT(0, memory_list->region_count());
+
+  MinidumpContext* context = exception->GetContext();
+  ASSERT_TRUE(context);
+
+  u_int64_t instruction_pointer;
+  switch (context->GetContextCPU()) {
+  case MD_CONTEXT_X86:
+    instruction_pointer = context->GetContextX86()->eip;
+    break;
+  case MD_CONTEXT_AMD64:
+    instruction_pointer = context->GetContextAMD64()->rip;
+    break;
+  case MD_CONTEXT_ARM:
+    instruction_pointer = context->GetContextARM()->iregs[15];
+    break;
+  default:
+    FAIL() << "Unknown context CPU: " << context->GetContextCPU();
+    break;
+  }
+
+  MinidumpMemoryRegion* region =
+    memory_list->GetMemoryRegionForAddress(instruction_pointer);
+  EXPECT_TRUE(region);
+  //TODO(ted): verify contents of memory region

[mochalatte, 2010/09/16 20:50:22]

if verifying the contents is too complicated for this iteration, is it possible
to at least do some checks on the size?

+
+  unlink(minidump_filename.c_str());
   free(filename);
 }
 
 static const unsigned kControlMsgSize =
     CMSG_SPACE(sizeof(int)) + CMSG_SPACE(sizeof(struct ucred));
 
 static bool
 CrashHandler(const void* crash_context, size_t crash_context_size,
              void* context) {
   const int fd = (intptr_t) context;
@@ skipping 97 matching lines @@
   int status;
   ASSERT_NE(HANDLE_EINTR(waitpid(child, &status, 0)), -1);
   ASSERT_TRUE(WIFSIGNALED(status));
   ASSERT_EQ(WTERMSIG(status), SIGSEGV);
 
   struct stat st;
   ASSERT_EQ(stat(templ, &st), 0);
   ASSERT_GT(st.st_size, 0u);
   unlink(templ);
 }