rxrpc: Fix rxrpc_input_call_event() to only unshare DATA packets

Fix rxrpc_input_call_event() to only unshare DATA packets and not ACK,
ABORT, etc..

And with that, rxrpc_input_packet() doesn't need to take a pointer to the
pointer to the packet, so change that to just a pointer.

Fixes: 1f27401 ("rxrpc: Fix potential UAF after skb_unshare() failure")
Closes: https://sashiko.dev/#/patchset/[email protected]
Signed-off-by: David Howells <[email protected]>
cc: Marc Dionne <[email protected]>
cc: Jeffrey Altman <[email protected]>
cc: Simon Horman <[email protected]>
cc: [email protected]
cc: [email protected]
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: dhowells

net/rxrpc/call_event.c

@@ -332,7 +332,8 @@ bool rxrpc_input_call_event(struct rxrpc_call *call)
 
 			saw_ack |= sp->hdr.type == RXRPC_PACKET_TYPE_ACK;
 
-			if (sp->hdr.securityIndex != 0 &&
+			if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
+			    sp->hdr.securityIndex != 0 &&
 			    skb_cloned(skb)) {
 				/* Unshare the packet so that it can be
 				 * modified by in-place decryption.