Messages in this thread |  | | | Date | Fri, 07 Aug 2009 09:20:09 +0800 | | From | Li Zefan <> | | Subject | Re: [PATCH 3/3] tracing/filters: Support filtering for char * strings |
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>> if (is_string_field(field)) { >> + pred->str_len = field->size; >> + >> if (field->filter_type == FILTER_STATIC_STRING) >> fn = filter_pred_string; >> - else >> + else if (field->filter_type == FILTER_DYN_STRING) >> fn = filter_pred_strloc; >> - pred->str_len = field->size; >> + else { >> + fn = filter_pred_pchar; >> + pred->str_len = strlen(pred->str_val); >> + } > > I'm a little dense here, where do we protect against someone making a > tracepoint that points to unsafe data? >
We can't prevent anyone from doing insane things deliberately, but we prevent from doing wrong things unconsciously.
Only if a TRACE_EVENT has a field defined as:
__field_ext(char *, name, FILTER_PTR_STR)
Here using FILTER_PTR_STR explicitly, he should know what he's doing.
Anyway, he can make a ptr pointing to unsafe data this way:
TP_STRUCT__entry( __field(char *, name) ) TP_printk("%s", name)
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