queue-6.6/sunrpc-wait-for-in-flight-client-tls-handshake-callback.patch

From a89dd597458848b463d284b15e42a8078beeb046 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=A9r=C3=A9my=20Jean?= <Jeremy.Jean@oss.cyber.gouv.fr>
Date: Sun, 9 Aug 2026 17:07:48 +0000
Subject: SUNRPC: wait for in-flight client TLS handshake callback
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From: Jérémy Jean <Jeremy.Jean@oss.cyber.gouv.fr>

commit a89dd597458848b463d284b15e42a8078beeb046 upstream.

xs_tls_handshake_sync() gives xs_tls_handshake_done() a reference to the
lower transport before submitting the handshake request. On timeout or
signal, the synchronous waiter drops that reference after calling
tls_handshake_cancel().

handshake_req_cancel() returns false when handshake_complete() has
already marked the request complete. In that case the completion callback
can still be running, so dropping the callback-owned reference in the
waiter can free the lower transport before xs_tls_handshake_done() stores
xprt_err or drops its own reference.

If cancellation loses to completion, wait until xs_tls_handshake_done()
signals handshake_done and let the callback release its reference. This
mirrors the server-side handshake lifetime handling and keeps the timeout
or signal return value unchanged.

Fixes: 75eb6af7acdf ("SUNRPC: Add a TCP-with-TLS RPC transport class")
Cc: stable@vger.kernel.org
Assisted-by: Codex:gpt-5
Signed-off-by: Jérémy Jean <Jeremy.Jean@oss.cyber.gouv.fr>
Reviewed-by: Chuck Lever <cel@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/sunrpc/xprtsock.c |   12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -2627,7 +2627,17 @@ static int xs_tls_handshake_sync(struct
 	rc = wait_for_completion_interruptible_timeout(&lower_transport->handshake_done,
 						       XS_TLS_HANDSHAKE_TO);
 	if (rc <= 0) {
-		tls_handshake_cancel(sk);
+		if (!tls_handshake_cancel(sk)) {
+			/*
+			 * Cancellation lost to handshake_complete(): the
+			 * callback still owns its xprt reference and is in
+			 * flight. Wait for it to finish before returning.
+			 */
+			wait_for_completion(&lower_transport->handshake_done);
+			if (rc == 0)
+				rc = -ETIMEDOUT;
+			goto out;
+		}
 		if (rc == 0)
 			rc = -ETIMEDOUT;
 		goto out_put_xprt;