http2: fix tracking received data for maxSessionMemory

src/node_http2.cc

@@ -1782,11 +1782,13 @@ void Http2Session::OnStreamRead(ssize_t nread, const uv_buf_t& buf_) {
   // Shrink to the actual amount of used data.
   buf.Resize(nread);
 
-  IncrementCurrentSessionMemory(buf.size());
+  IncrementCurrentSessionMemory(nread);
   OnScopeLeave on_scope_leave([&]() {
     // Once finished handling this write, reset the stream buffer.
     // The memory has either been free()d or was handed over to V8.
-    DecrementCurrentSessionMemory(buf.size());
+    // We use `nread` instead of `buf.size()` here, because the buffer is
+    // cleared as part of the `.ToArrayBuffer()` call below.
+    DecrementCurrentSessionMemory(nread);
     stream_buf_ab_ = Local<ArrayBuffer>();
     stream_buf_ = uv_buf_init(nullptr, 0);
   });

test/parallel/test-http2-max-session-memory-leak.js

@@ -0,0 +1,46 @@
+'use strict';
+const common = require('../common');
+if (!common.hasCrypto)
+  common.skip('missing crypto');
+const http2 = require('http2');
+
+// Regression test for https://github.com/nodejs/node/issues/27416.
+// Check that received data is accounted for correctly in the maxSessionMemory
+// mechanism.
+
+const bodyLength = 8192;
+const maxSessionMemory = 1;  // 1 MB
+const requestCount = 1000;
+
+const server = http2.createServer({ maxSessionMemory });
+server.on('stream', (stream) => {
+  stream.respond();
+  stream.end();
+});
+
+server.listen(common.mustCall(() => {
+  const client = http2.connect(`http://localhost:${server.address().port}`, {
+    maxSessionMemory
+  });
+
+  function request() {
+    return new Promise((resolve, reject) => {
+      const stream = client.request({
+        ':method': 'POST',
+        'content-length': bodyLength
+      });
+      stream.on('error', reject);
+      stream.on('response', resolve);
+      stream.end('a'.repeat(bodyLength));
+    });
+  }
+
+  (async () => {
+    for (let i = 0; i < requestCount; i++) {
+      await request();
+    }
+
+    client.close();
+    server.close();
+  })().then(common.mustCall());
+}));