diff --git a/compiler-rt/lib/scudo/standalone/combined.h b/compiler-rt/lib/scudo/standalone/combined.h
--- a/compiler-rt/lib/scudo/standalone/combined.h
+++ b/compiler-rt/lib/scudo/standalone/combined.h
@@ -903,6 +903,10 @@
 
   void setTrackAllocationStacks(bool Track) {
     initThreadMaybe();
+    if (getFlags()->allocation_ring_buffer_size == 0) {
+      DCHECK(!Primary.Options.get(OptionsBit::TrackAllocationStacks));
+      return;
+    }
     if (Track)
       Primary.Options.set(OptionBit::TrackAllocationStacks);
     else
@@ -1066,6 +1070,10 @@
   // Pointer to memory mapped area starting with AllocationRingBuffer struct,
   // and immediately followed by Size elements of type Entry.
   char *RawRingBuffer = {};
+  // If we disable allocation tracking, we give a zero-sized
+  // AllocationRingBuffer to the client code. This is slightly wasteful
+  // (we use 128 bytes on a 64-bit platform), but simplifies the code.
+  AllocationRingBuffer PlaceholderRingBuffer = {};
 
   // The following might get optimized out by the compiler.
   NOINLINE void performSanityChecks() {
@@ -1408,8 +1416,8 @@
                                      const char *RingBufferPtr) {
     auto *RingBuffer =
         reinterpret_cast<const AllocationRingBuffer *>(RingBufferPtr);
-    if (!RingBuffer)
-      return; //  just in case; called before init
+    if (!RingBuffer || RingBuffer->Size == 0)
+      return;
     uptr Pos = atomic_load_relaxed(&RingBuffer->Pos);
 
     for (uptr I = Pos - 1;
@@ -1495,9 +1503,14 @@
   void initRingBuffer() {
     u32 AllocationRingBufferSize =
         static_cast<u32>(getFlags()->allocation_ring_buffer_size);
-    // Have at least one entry so we don't need to special case.
-    if (AllocationRingBufferSize < 1)
-      AllocationRingBufferSize = 1;
+    // If allocation_ring_buffer_size is zero we allocate a placeholder as not
+    // to confuse downstream users of this buffer, but we don't use it because
+    // we disallow setTrackAllocationStacks.
+    if (AllocationRingBufferSize < 1) {
+      DCHECK(PlaceholderRingBuffer->Size == 0);
+      RawRingBuffer = reinterpret_cast<char *>(&PlaceholderRingBuffer);
+      return;
+    }
     MapPlatformData Data = {};
     RawRingBuffer = static_cast<char *>(
         map(/*Addr=*/nullptr,