[PATCH v4 01/21] afs: handle CB.InitCallBackState3 requests without a server record

[David Howells <dhowells@redhat.com>]

From: Nan Li <tonanli66@gmail.com>

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@kernel.org
Reported-by: Yuan Tan <yuantan098@gmail.com>
Reported-by: Yifan Wu <yifanwucs@gmail.com>
Reported-by: Juefei Pu <tomapufckgml@gmail.com>
Reported-by: Xin Liu <bird@lzu.edu.cn>
Signed-off-by: Nan Li <tonanli66@gmail.com>
Signed-off-by: Ren Wei <n05ec@lzu.edu.cn>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
---
 fs/afs/cmservice.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/afs/cmservice.c b/fs/afs/cmservice.c
index 5540ae1cad59..263c60c811a5 100644
--- a/fs/afs/cmservice.c
+++ b/fs/afs/cmservice.c
@@ -364,6 +364,11 @@ static int afs_deliver_cb_init_call_back_state3(struct afs_call *call)
 	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);