[PATCH 7.1 0036/2077] afs: handle CB.InitCallBackState3 requests without a server record

[Greg Kroah-Hartman]

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

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

From: Nan Li <tonanli66 at gmail.com>

commit f3cf725cd284b7912d5522babb44721bf38c8887 upstream.

The cache manager callback path now attaches the server record to an
incoming call through the rxrpc peer's app data.  That association is
not guaranteed to exist for every callback request, and most callback
handlers already tolerate that case.

Make CB.InitCallBackState3 follow the same pattern by checking whether a
server record was attached before using it.  If the peer is not mapped
to a server record, trace the request and ignore it, matching the
existing behaviour for other unmatched callback requests.

This keeps the callback handler consistent with the rest of the cache
manager service and avoids depending on peer state that may not be
available for a given request.

Fixes: 40e8b52fe8c8 ("afs: Use the per-peer app data provided by rxrpc")
Cc: stable at kernel.org
Reported-by: Yuan Tan <yuantan098 at gmail.com>
Reported-by: Yifan Wu <yifanwucs at gmail.com>
Reported-by: Juefei Pu <tomapufckgml at gmail.com>
Reported-by: Xin Liu <bird at lzu.edu.cn>
Signed-off-by: Nan Li <tonanli66 at gmail.com>
Signed-off-by: Ren Wei <n05ec at lzu.edu.cn>
Signed-off-by: David Howells <dhowells at redhat.com>
Link: https://patch.msgid.link/20260622090856.2746629-2-dhowells@redhat.com
cc: Marc Dionne <marc.dionne at auristor.com>
cc: linux-afs at lists.infradead.org
Signed-off-by: Christian Brauner (Amutable) <brauner at kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 fs/afs/cmservice.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/fs/afs/cmservice.c
+++ b/fs/afs/cmservice.c
@@ -364,6 +364,11 @@ static int afs_deliver_cb_init_call_back
 	if (!afs_check_call_state(call, AFS_CALL_SV_REPLYING))
 		return afs_io_error(call, afs_io_error_cm_reply);
 
+	if (!call->server) {
+		trace_afs_cm_no_server_u(call, call->request);
+		return 0;
+	}
+
 	if (memcmp(call->request, &call->server->_uuid, sizeof(call->server->_uuid)) != 0) {
 		pr_notice("Callback UUID does not match fileserver UUID\n");
 		trace_afs_cm_no_server_u(call, call->request);