4 files changed, 48 insertions, 20 deletions

diff --git a/core/fxcrt/fx_memory.cpp b/core/fxcrt/fx_memory.cpp
index 6a135ae0f8..006e03031e 100644
--- a/core/fxcrt/fx_memory.cpp
+++ b/core/fxcrt/fx_memory.cpp
@@ -35,8 +35,9 @@ void* FXMEM_DefaultCalloc(size_t num_elems, size_t byte_size) {
 }
 
 void* FXMEM_DefaultRealloc(void* pointer, size_t new_size) {
-  return pdfium::base::PartitionReallocGeneric(
-      gGeneralPartitionAllocator.root(), pointer, new_size, "GeneralPartition");
+  return pdfium::base::PartitionReallocGenericFlags(
+      gGeneralPartitionAllocator.root(), pdfium::base::PartitionAllocReturnNull,
+      pointer, new_size, "GeneralPartition");
 }
 
 void FXMEM_DefaultFree(void* pointer) {
diff --git a/core/fxcrt/fx_memory.h b/core/fxcrt/fx_memory.h
index f7e6d67520..707e084211 100644
--- a/core/fxcrt/fx_memory.h
+++ b/core/fxcrt/fx_memory.h
@@ -57,9 +57,9 @@ inline void* FX_SafeRealloc(void* ptr, size_t num_members, size_t member_size) {
   if (!size.IsValid())
     return nullptr;
 
-  return pdfium::base::PartitionReallocGeneric(
-      gGeneralPartitionAllocator.root(), ptr, size.ValueOrDie(),
-      "GeneralPartition");
+  return pdfium::base::PartitionReallocGenericFlags(
+      gGeneralPartitionAllocator.root(), pdfium::base::PartitionAllocReturnNull,
+      ptr, size.ValueOrDie(), "GeneralPartition");
 }
 
 inline void* FX_AllocOrDie(size_t num_members, size_t member_size) {
diff --git a/third_party/base/allocator/partition_allocator/partition_alloc.cc b/third_party/base/allocator/partition_allocator/partition_alloc.cc
index ff366b861f..e8aad9420c 100644
--- a/third_party/base/allocator/partition_allocator/partition_alloc.cc
+++ b/third_party/base/allocator/partition_allocator/partition_alloc.cc
@@ -1021,22 +1021,29 @@ bool partitionReallocDirectMappedInPlace(PartitionRootGeneric* root,
   return true;
 }
 
-void* PartitionReallocGeneric(PartitionRootGeneric* root,
-                              void* ptr,
-                              size_t new_size,
-                              const char* type_name) {
+void* PartitionReallocGenericFlags(PartitionRootGeneric* root,
+                                   int flags,
+                                   void* ptr,
+                                   size_t new_size,
+                                   const char* type_name) {
 #if defined(MEMORY_TOOL_REPLACES_ALLOCATOR)
-  return realloc(ptr, new_size);
+  void* result = realloc(ptr, new_size);
+  CHECK(result || flags & PartitionAllocReturnNull);
+  return result;
 #else
   if (UNLIKELY(!ptr))
-    return PartitionAllocGeneric(root, new_size, type_name);
+    return PartitionAllocGenericFlags(root, flags, new_size, type_name);
   if (UNLIKELY(!new_size)) {
     PartitionFreeGeneric(root, ptr);
-    return 0;
+    return nullptr;
   }
 
-  if (new_size > kGenericMaxDirectMapped)
-    PartitionExcessiveAllocationSize();
+  if (new_size > kGenericMaxDirectMapped) {
+    if (flags & PartitionAllocReturnNull)
+      return nullptr;
+    else
+      PartitionExcessiveAllocationSize();
+  }
 
   DCHECK(PartitionPointerIsValid(PartitionCookieFreePointerAdjust(ptr)));
 
@@ -1069,12 +1076,19 @@ void* PartitionReallocGeneric(PartitionRootGeneric* root,
     // |new_size| via the raw size pointer.
     if (PartitionPageGetRawSizePtr(page))
       PartitionCookieWriteValue(static_cast<char*>(ptr) + new_size);
-#endif
+#endif  // DCHECK_IS_ON()
     return ptr;
   }
 
   // This realloc cannot be resized in-place. Sadness.
-  void* ret = PartitionAllocGeneric(root, new_size, type_name);
+  void* ret = PartitionAllocGenericFlags(root, flags, new_size, type_name);
+  if (!ret) {
+    if (flags & PartitionAllocReturnNull)
+      return nullptr;
+    else
+      PartitionExcessiveAllocationSize();
+  }
+
   size_t copy_size = actual_old_size;
   if (new_size < copy_size)
     copy_size = new_size;
@@ -1082,7 +1096,14 @@ void* PartitionReallocGeneric(PartitionRootGeneric* root,
   memcpy(ret, ptr, copy_size);
   PartitionFreeGeneric(root, ptr);
   return ret;
-#endif
+#endif  // defined(MEMORY_TOOL_REPLACES_ALLOCATOR)
+}
+
+void* PartitionReallocGeneric(PartitionRootGeneric* root,
+                              void* ptr,
+                              size_t new_size,
+                              const char* type_name) {
+  return PartitionReallocGenericFlags(root, 0, ptr, new_size, type_name);
 }
 
 static size_t PartitionPurgePage(PartitionPage* page, bool discard) {
diff --git a/third_party/base/allocator/partition_allocator/partition_alloc.h b/third_party/base/allocator/partition_allocator/partition_alloc.h
index 87db329af2..69fba97d62 100644
--- a/third_party/base/allocator/partition_allocator/partition_alloc.h
+++ b/third_party/base/allocator/partition_allocator/partition_alloc.h
@@ -432,9 +432,15 @@ BASE_EXPORT NOINLINE void* PartitionAllocSlowPath(PartitionRootBase*,
                                                   size_t,
                                                   PartitionBucket*);
 BASE_EXPORT NOINLINE void PartitionFreeSlowPath(PartitionPage*);
-BASE_EXPORT NOINLINE void* PartitionReallocGeneric(PartitionRootGeneric*,
-                                                   void*,
-                                                   size_t,
+BASE_EXPORT NOINLINE void* PartitionReallocGenericFlags(
+    PartitionRootGeneric* root,
+    int flags,
+    void* ptr,
+    size_t new_size,
+    const char* type_name);
+BASE_EXPORT NOINLINE void* PartitionReallocGeneric(PartitionRootGeneric* root,
+                                                   void* ptr,
+                                                   size_t new_size,
                                                    const char* type_name);
 
 BASE_EXPORT void PartitionDumpStats(PartitionRoot*,