From e7bbab94629c3dd4aee59fc475a3ae68e35d7498 Mon Sep 17 00:00:00 2001
From: Mike McLaughlin <mikem@microsoft.com>
Date: Thu, 13 Dec 2018 09:40:37 -0800
Subject: [PATCH] Fix issue #21484 - createdump segfaults with ASP.NET app

The problem is the ClrDataModule Request faulted on a dynamic module
getting the file layout flag.

Fixed the Request code not get the file layout and in the crash dump
code skip any dynamic modules.
---
 src/debug/createdump/crashinfo.cpp | 34 +++++++++++++++++++++---------
 src/debug/daccess/task.cpp         |  7 +++++-
 2 files changed, 30 insertions(+), 11 deletions(-)

diff --git a/src/debug/createdump/crashinfo.cpp b/src/debug/createdump/crashinfo.cpp
index 6de6b94429a1..4db2b00eeb9f 100644
--- a/src/debug/createdump/crashinfo.cpp
+++ b/src/debug/createdump/crashinfo.cpp
@@ -708,6 +708,17 @@ CrashInfo::EnumerateManagedModules(IXCLRDataProcess* pClrDataProcess)
             break;
         }
 
+        // Skip any dynamic modules. The Request call below on some DACs crashes on dynamic modules.
+        ULONG32 flags;
+        if ((hr = pClrDataModule->GetFlags(&flags)) != S_OK) {
+            TRACE("MODULE: GetFlags FAILED %08x\n", hr);
+            continue;
+        }
+        if (flags & CLRDATA_MODULE_IS_DYNAMIC) {
+            TRACE("MODULE: Skipping dynamic module\n");
+            continue;
+        }
+
         DacpGetModuleData moduleData;
         if (SUCCEEDED(hr = moduleData.Request(pClrDataModule.GetPtr())))
         {
@@ -719,17 +730,20 @@ CrashInfo::EnumerateManagedModules(IXCLRDataProcess* pClrDataProcess)
                 ArrayHolder<WCHAR> wszUnicodeName = new WCHAR[MAX_LONGPATH + 1];
                 if (SUCCEEDED(hr = pClrDataModule->GetFileName(MAX_LONGPATH, nullptr, wszUnicodeName)))
                 {
-                    char* pszName = (char*)malloc(MAX_LONGPATH + 1);
-                    if (pszName == nullptr) {
-                        fprintf(stderr, "Allocating module name FAILED\n");
-                        result = false;
-                        break;
+                    // If the module file name isn't empty
+                    if (wszUnicodeName[0] != 0) {
+                        char* pszName = (char*)malloc(MAX_LONGPATH + 1);
+                        if (pszName == nullptr) {
+                            fprintf(stderr, "Allocating module name FAILED\n");
+                            result = false;
+                            break;
+                        }
+                        sprintf_s(pszName, MAX_LONGPATH, "%S", (WCHAR*)wszUnicodeName);
+                        TRACE(" %s\n", pszName);
+
+                        // Change the module mapping name
+                        ReplaceModuleMapping(moduleData.LoadedPEAddress, pszName);
                     }
-                    sprintf_s(pszName, MAX_LONGPATH, "%S", (WCHAR*)wszUnicodeName);
-                    TRACE(" %s\n", pszName);
-
-                    // Change the module mapping name
-                    ReplaceModuleMapping(moduleData.LoadedPEAddress, pszName);
                 }
                 else {
                     TRACE("\nModule.GetFileName FAILED %08x\n", hr);
diff --git a/src/debug/daccess/task.cpp b/src/debug/daccess/task.cpp
index 601ad401af62..d7d8ba5a8478 100644
--- a/src/debug/daccess/task.cpp
+++ b/src/debug/daccess/task.cpp
@@ -2745,7 +2745,12 @@ ClrDataModule::RequestGetModuleData(
         COUNT_T peSize;
         outGMD->LoadedPEAddress = TO_CDADDR(PTR_TO_TADDR(pPEFile->GetLoadedImageContents(&peSize)));
         outGMD->LoadedPESize = (ULONG64)peSize;
-        outGMD->IsFileLayout = pPEFile->GetLoaded()->IsFlat();
+
+        // Can not get the file layout for a dynamic module
+        if (!outGMD->IsDynamic)
+        {
+            outGMD->IsFileLayout = pPEFile->GetLoaded()->IsFlat();
+        }
     }
 
     // If there is a in memory symbol stream