Re: [PATCH v2] ftrace: Fix use-after-free for dynamic ftrace_ops
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2022-11-03 03:23:46
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On Thu, 3 Nov 2022 11:10:10 +0800 Li Huafei [off-list ref] wrote:
quoted hunk ↗ jump to hunk
--- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c@@ -3028,18 +3028,8 @@ int ftrace_shutdown(struct ftrace_ops *ops, int command) command |= FTRACE_UPDATE_TRACE_FUNC; } - if (!command || !ftrace_enabled) { - /* - * If these are dynamic or per_cpu ops, they still - * need their data freed. Since, function tracing is - * not currently active, we can just free them - * without synchronizing all CPUs. - */ - if (ops->flags & FTRACE_OPS_FL_DYNAMIC) - goto free_ops; - - return 0; - } + if (!command || !ftrace_enabled) + goto out;
Hi Li,
I think you misunderstood me. What I was suggesting was to get rid of
the ftrace_enabled check. The DYNAMIC part is most definitely needed.
if (!command) {
if (ops->flags & FTRACE_OPS_FL_DYNAMIC)
goto out;
return 0;
}
-- Steve