[PATCH 6.6 388/484] rxrpc: Fix socket notification race

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

From: David Howells <dhowells@redhat.com>

[ Upstream commit e66f8f32f50116670dbbee5bc9e692cd2cd0c8f8 ]

There's a race between rxrpc_recvmsg() and rxrpc_notify_socket(), whereby
the latter's attempt to avoid disabling interrupts and taking the socket's
recvmsg_lock if the call is already queued may happen simultaneously with
the former's discarding of a call that has nothing queued.

Fix this by removing the shortcut.  Note that this only affects userspace's
use of AF_RXRPC; the AFS filesystem driver doesn't use the socket queue.

Fixes: 248f219cb8bc ("rxrpc: Rewrite the data and ack handling code")
Link: https://sashiko.dev/#/patchset/20260616155749.2125907-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: Jeffrey Altman <jaltman@auristor.com>
cc: Simon Horman <horms@kernel.org>
cc: linux-afs@lists.infradead.org
cc: stable@kernel.org
Link: https://patch.msgid.link/20260624163819.3017002-10-dhowells@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/rxrpc/recvmsg.c |    2 --
 1 file changed, 2 deletions(-)

--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -27,8 +27,6 @@ void rxrpc_notify_socket(struct rxrpc_ca
 
 	_enter("%d", call->debug_id);
 
-	if (!list_empty(&call->recvmsg_link))
-		return;
 	if (test_bit(RXRPC_CALL_RELEASED, &call->flags)) {
 		rxrpc_see_call(call, rxrpc_call_see_notify_released);
 		return;