| Date | Mon, 6 Nov 2023 18:55:13 -0500 | From | Steven Rostedt <> | Subject | Re: [PATCH v1 04/12] dyndbg: add 2 trace-events: pr_debug, dev_dbg |
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On Fri, 3 Nov 2023 14:10:03 +0100 Łukasz Bartosik <lb@semihalf.com> wrote:
> +/* capture pr_debug() callsite descriptor and message */ > +TRACE_EVENT(prdbg, > + TP_PROTO(const struct _ddebug *desc, const char *text, size_t len), > + > + TP_ARGS(desc, text, len), > + > + TP_STRUCT__entry( > + __field(const struct _ddebug *, desc) > + __dynamic_array(char, msg, len + 1) > + ), > + > + TP_fast_assign( > + __entry->desc = desc; > + /* > + * Each trace entry is printed in a new line. > + * If the msg finishes with '\n', cut it off > + * to avoid blank lines in the trace. > + */ > + if (len > 0 && (text[len - 1] == '\n')) > + len -= 1; > + > + memcpy(__get_str(msg), text, len); > + __get_str(msg)[len] = 0; > + ), > +
> + TP_printk("%s.%s %s", __entry->desc->modname, > + __entry->desc->function, __get_str(msg)) > +); > +
That TP_printk() is dangerous. How do you know __entry->desc still exists when reading the buffer?
Is the struct _ddebug permanent? Can it be freed? If so, the above can easily cause a crash.
-- Steve
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