[PATCH 7.1 0031/2077] rxrpc: Fix the reception of a reply packet before data transmission

[Greg Kroah-Hartman]

7.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells at redhat.com>

commit a58e33405acd2584e730c1da72635f822ada6b49 upstream.

Fix rxrpc_receiving_reply() to handle the reception of an apparent reply
DATA packet before rxrpc has had a chance to send any request DATA packets
on a client call by checking to see if the call has been exposed yet by
sending the first packet.

Without this, rxrpc_rotate_tx_window() might oops.

Also fix rxrpc_rotate_tx_window() to handle the Tx queue being empty by
changing the do...while loop into a while loop, just in case a call is
abnormally terminated by an early reply before the last request packet is
transmitted.

Fixes: b341a0263b1b ("rxrpc: Implement progressive transmission queue struct")
Link: https://sashiko.dev/#/patchset/20260616155749.2125907-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells at redhat.com>
cc: Marc Dionne <marc.dionne at auristor.com>
cc: Jeffrey Altman <jaltman at auristor.com>
cc: Simon Horman <horms at kernel.org>
cc: linux-afs at lists.infradead.org
cc: stable at kernel.org
Link: https://patch.msgid.link/20260624163819.3017002-7-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba at kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 net/rxrpc/input.c |   13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -251,7 +251,7 @@ static bool rxrpc_rotate_tx_window(struc
 		tq = call->tx_queue;
 	}
 
-	do {
+	while (before_eq(seq, to)) {
 		unsigned int ix = seq - call->tx_qbase;
 
 		_debug("tq=%x seq=%x i=%d f=%x", tq->qbase, seq, ix, tq->bufs[ix]->flags);
@@ -321,8 +321,7 @@ static bool rxrpc_rotate_tx_window(struc
 				break;
 			}
 		}
-
-	} while (before_eq(seq, to));
+	}
 
 	if (trace)
 		trace_rxrpc_rack_update(call, summary);
@@ -397,6 +396,14 @@ static bool rxrpc_receiving_reply(struct
 		trace_rxrpc_timer_can(call, rxrpc_timer_trace_delayed_ack);
 	}
 
+	/* Deal with an apparent reply coming in before we've got the request
+	 * queued or transmitted.
+	 */
+	if (!test_bit(RXRPC_CALL_EXPOSED, &call->flags)) {
+		rxrpc_proto_abort(call, top, rxrpc_eproto_early_reply);
+		return false;
+	}
+
 	if (!test_bit(RXRPC_CALL_TX_LAST, &call->flags)) {
 		if (!rxrpc_rotate_tx_window(call, top, &summary)) {
 			rxrpc_proto_abort(call, top, rxrpc_eproto_early_reply);