[ruby/zlib] Synchronize access to zstream to prevent segfault in multithreaded use

I'm not sure whether this handles all multithreaded use cases,
but this handles the example that crashes almost immediately
and does 10,000,000 total deflates using 100 separate threads.

To prevent the tests from taking forever, the committed test
for this uses only 10,000 deflates across 10 separate threads,
which still causes a segfault in the previous implementation
almost immediately.

Fixes [Bug #17803]

https://github.com/ruby/zlib/commit/4b1023b3f2

1 files changed, 61 insertions, 0 deletions

diff --git a/test/zlib/test_zlib.rb b/test/zlib/test_zlib.rb
index be0570165e..4780bc077b 100644
--- a/test/zlib/test_zlib.rb
+++ b/test/zlib/test_zlib.rb
@@ -4,6 +4,7 @@ require 'test/unit'
 require 'stringio'
 require 'tempfile'
 require 'tmpdir'
+require 'securerandom'
 
 begin
   require 'zlib'
@@ -503,6 +504,66 @@ if defined? Zlib
       assert_raise(Zlib::StreamError) { z.set_dictionary("foo") }
       z.close
     end
+
+    def test_multithread_deflate
+      zd = Zlib::Deflate.new
+
+      s = "x" * 10000
+      (0...10).map do |x|
+        Thread.new do
+          1000.times { zd.deflate(s) }
+        end
+      end.each do |th|
+        th.join
+      end
+    ensure
+      zd&.finish
+      zd&.close
+    end
+
+    def test_multithread_inflate
+      zi = Zlib::Inflate.new
+
+      s = Zlib.deflate("x" * 10000)
+      (0...10).map do |x|
+        Thread.new do
+          1000.times { zi.inflate(s) }
+        end
+      end.each do |th|
+        th.join
+      end
+    ensure
+      zi&.finish
+      zi&.close
+    end
+
+    def test_recursive_deflate
+      zd = Zlib::Deflate.new
+
+      s = SecureRandom.random_bytes(1024**2)
+      assert_raise(Zlib::BufError) do
+        zd.deflate(s) do
+          zd.deflate(s)
+        end
+      end
+    ensure
+      zd&.finish
+      zd&.close
+    end
+
+    def test_recursive_inflate
+      zi = Zlib::Inflate.new
+
+      s = Zlib.deflate(SecureRandom.random_bytes(1024**2))
+
+      assert_raise(Zlib::DataError) do
+        zi.inflate(s) do
+          zi.inflate(s)
+        end
+      end
+    ensure
+      zi&.close
+    end
   end
 
   class TestZlibGzipFile < Test::Unit::TestCase