merge revision(s) b3d62a77d928eff01268ca7fa1c1c0966702926d: [Backport #17803]

	[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
	---
	 ext/zlib/zlib.c        | 33 ++++++++++++++++++++++++++-
	 test/zlib/test_zlib.rb | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++
	 2 files changed, 93 insertions(+), 1 deletion(-)

3 files changed, 94 insertions, 2 deletions

diff --git a/ext/zlib/zlib.c b/ext/zlib/zlib.c
index fdf92e29f1..d5a1bf65e6 100644
--- a/ext/zlib/zlib.c
+++ b/ext/zlib/zlib.c
@@ -546,6 +546,7 @@ struct zstream {
     unsigned long flags;
     VALUE buf;
     VALUE input;
+    VALUE mutex;
     z_stream stream;
     const struct zstream_funcs {
 	int (*reset)(z_streamp);
@@ -621,6 +622,7 @@ zstream_init(struct zstream *z, const struct zstream_funcs *func)
     z->flags = 0;
     z->buf = Qnil;
     z->input = Qnil;
+    z->mutex = rb_mutex_new();
     z->stream.zalloc = zlib_mem_alloc;
     z->stream.zfree = zlib_mem_free;
     z->stream.opaque = Z_NULL;
@@ -652,7 +654,9 @@ zstream_expand_buffer(struct zstream *z)
 	        rb_obj_reveal(z->buf, rb_cString);
             }
 
+            rb_mutex_unlock(z->mutex);
 	    rb_protect(rb_yield, z->buf, &state);
+            rb_mutex_lock(z->mutex);
 
             if (ZSTREAM_REUSE_BUFFER_P(z)) {
                 rb_str_modify(z->buf);
@@ -1054,7 +1058,7 @@ zstream_unblock_func(void *ptr)
 }
 
 static void
-zstream_run(struct zstream *z, Bytef *src, long len, int flush)
+zstream_run0(struct zstream *z, Bytef *src, long len, int flush)
 {
     struct zstream_run_args args;
     int err;
@@ -1138,6 +1142,32 @@ loop:
 	rb_jump_tag(args.jump_state);
 }
 
+struct zstream_run_synchronized_args {
+    struct zstream *z;
+    Bytef *src;
+    long len;
+    int flush;
+};
+
+static VALUE
+zstream_run_synchronized(VALUE value_arg)
+{
+    struct zstream_run_synchronized_args *run_args = (struct zstream_run_synchronized_args *)value_arg;
+    zstream_run0(run_args->z, run_args->src, run_args->len, run_args->flush);
+    return Qnil;
+}
+
+static void
+zstream_run(struct zstream *z, Bytef *src, long len, int flush)
+{
+    struct zstream_run_synchronized_args run_args;
+    run_args.z = z;
+    run_args.src = src;
+    run_args.len = len;
+    run_args.flush = flush;
+    rb_mutex_synchronize(z->mutex, zstream_run_synchronized, (VALUE)&run_args);
+}
+
 static VALUE
 zstream_sync(struct zstream *z, Bytef *src, long len)
 {
@@ -1183,6 +1213,7 @@ zstream_mark(void *p)
     struct zstream *z = p;
     rb_gc_mark(z->buf);
     rb_gc_mark(z->input);
+    rb_gc_mark(z->mutex);
 }
 
 static void
diff --git a/test/zlib/test_zlib.rb b/test/zlib/test_zlib.rb
index a51a00d329..a5fc9056c8 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
diff --git a/version.h b/version.h
index 6cd54a49f9..1564bfe8ee 100644
--- a/version.h
+++ b/version.h
@@ -12,7 +12,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 4
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 178
+#define RUBY_PATCHLEVEL 179
 
 #define RUBY_RELEASE_YEAR 2022
 #define RUBY_RELEASE_MONTH 2