ftrace: Using FTRACE_WARN_ON() to check "freed record" in ftrace_release()
"Because when we call ftrace_free_rec we change the rec->ip to point to the next record in the chain. Something is very wrong if rec->ip >= s && rec->ip < e and the record is already free." "Note, use FTRACE_WARN_ON() macro. This way it shuts down ftrace if it is hit and helps to avoid further damage later." -- Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com>
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1 changed files with 7 additions and 2 deletions
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@ -358,9 +358,14 @@ void ftrace_release(void *start, unsigned long size)
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mutex_lock(&ftrace_lock);
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do_for_each_ftrace_rec(pg, rec) {
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if ((rec->ip >= s) && (rec->ip < e) &&
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!(rec->flags & FTRACE_FL_FREE))
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if ((rec->ip >= s) && (rec->ip < e)) {
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/*
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* rec->ip is changed in ftrace_free_rec()
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* It should not between s and e if record was freed.
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*/
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FTRACE_WARN_ON(rec->flags & FTRACE_FL_FREE);
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ftrace_free_rec(rec);
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}
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} while_for_each_ftrace_rec();
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mutex_unlock(&ftrace_lock);
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}
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