binder: fix test regression due to sender_euid change

This is a partial revert of commit
29bc22a ("binder: use euid from cred instead of using task").
Setting sender_euid using proc->cred caused some Android system test
regressions that need further investigation. It is a partial
reversion because subsequent patches rely on proc->cred.

Fixes: 29bc22a ("binder: use euid from cred instead of using task")
Cc: [email protected] # 4.4+
Acked-by: Christian Brauner <[email protected]>
Signed-off-by: Todd Kjos <[email protected]>
Change-Id: I9b1769a3510fed250bb21859ef8beebabe034c66
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: toddkjos

drivers/android/binder.c

@@ -2710,7 +2710,7 @@ static void binder_transaction(struct binder_proc *proc,
 		t->from = thread;
 	else
 		t->from = NULL;
-	t->sender_euid = proc->cred->euid;
+	t->sender_euid = task_euid(proc->tsk);
 	t->to_proc = target_proc;
 	t->to_thread = target_thread;
 	t->code = tr->code;