From eeff3f3a2a43eda2d5622724fe930fb2d79af67d Mon Sep 17 00:00:00 2001
From: Xinhao Yuan <xinhaoyuan@google.com>
Date: Tue, 25 Feb 2025 14:44:10 -0800
Subject: [PATCH] #Centipede Protect the shared mmap-ed buffers from forked
 processes.

This is a short-term solution that only works for Linux.

PiperOrigin-RevId: 731036490
---
 centipede/shared_memory_blob_sequence.cc | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/centipede/shared_memory_blob_sequence.cc b/centipede/shared_memory_blob_sequence.cc
index a60ad856..56108e6c 100644
--- a/centipede/shared_memory_blob_sequence.cc
+++ b/centipede/shared_memory_blob_sequence.cc
@@ -147,6 +147,11 @@ void SharedMemoryBlobSequence::MmapData() {
   data_ = static_cast<uint8_t *>(
       mmap(nullptr, size_, PROT_READ | PROT_WRITE, MAP_SHARED, fd_, 0));
   ErrorOnFailure(data_ == MAP_FAILED, "mmap() failed");
+#ifndef __APPLE__
+  // TODO: b/385774476 - this is a temporary and Linux-only solution to protect
+  // the mmap-ed region from forked processes.
+  ErrorOnFailure(madvise(data_, size_, MADV_DONTFORK), "madvise() failed");
+#endif
 }
 
 SharedMemoryBlobSequence::~SharedMemoryBlobSequence() {