[rbhanda]

Summary

Forward-port the released .NET 11 RC3 SocketAsyncEventArgs fix to main.

• Size the Windows native socket-address buffer from the current socket's address family, grow it when reused, and use the allocated buffer length for WSAMsg.
• Replace a cached managed SocketAddress when it is too small for the current socket.
• Preserve the regression tests for event-args reuse across IPv4/IPv6 and caller-supplied SocketAddress family mismatches.

Source

Clean forward-port of public commit 6f0fa48bddc8e7baaf5932d9340487ef12621103, included in public tag v11.0.0-rc.3.26522.148. No servicing version changes or unrelated fixes are included.

@wfurt, please review the forward-port and confirm the fix and regression coverage on main.

Validation

• git diff --check passed.
• The stable patch ID matches the published source commit; the three-file change applied without conflicts.
• Attempted the targeted System.Net.Sockets build locally. It stopped at SDK resolution: this checkout requires .NET SDK 11.0.100-rc.1.26420.103, which is not installed. The changed product and regression tests have not been built or executed locally.
• Windows build/test CI and owner approval are still required. This PR is intentionally a draft.

Note

This PR was prepared with GitHub Copilot.

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[Copilot]

🟡 Changes recommended

Native buffer growth frees the old allocation before its replacement succeeds, allowing a double-free if allocation fails.

1 open issue

• Allocate replacement buffer before freeing old socket address · New

What changed in this PR

Forward-ports the SocketAsyncEventArgs address-family reuse fix to main, updating socket-address buffer sizing and adding regression coverage in System.Net.Sockets.

Changes:

• Size Windows native buffers from the current socket’s address family, grow them as needed, and use the declared buffer length for WSAMsg.
• Replace cached managed socket-address buffers when too small.
• Add regression tests for IPv4/IPv6 event-args reuse and caller-supplied address-family mismatches.

File	Description
src/​runtime/​src/​libraries/​System.Net.Sockets/​tests/​FunctionalTests/​ReceiveFrom.cs	Adds cross-family reuse and family-mismatch regression tests.
src/​runtime/​src/​libraries/​System.Net.Sockets/​src/​System/​Net/​Sockets/​SocketAsyncEventArgs.Windows.cs	Tracks native buffer capacity and adjusts allocation and WSAMsg sizing.
src/​runtime/​src/​libraries/​System.Net.Sockets/​src/​System/​Net/​Sockets/​Socket.cs	Replaces undersized cached managed socket-address buffers.

_{Review effort: Balanced}