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Subject[PATCH v4 7/7] tracing: Change synthetic event string format to limit printed length
Date
From: Steven Rostedt <rostedt@goodmis.org>

Change the format for printing synthetic field strings to limit the
length of the string printed even if it's not correctly terminated.

Description from Steve:

I also added this for a bit of paranoid, and probably should be a
separate patch, just to make sure if the string isn't nul terminated,
this will keep it from bleeding pass the end of the string.
---
kernel/trace/trace_events_synth.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index 24bc6d61aa40..742ce5f62d6d 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -234,7 +234,7 @@ static const char *synth_field_fmt(char *type)
else if (strcmp(type, "gfp_t") == 0)
fmt = "%x";
else if (synth_field_is_string(type))
- fmt = "%s";
+ fmt = "%.*s";

return fmt;
}
@@ -303,11 +303,13 @@ static enum print_line_t print_synth_event(struct trace_iterator *iter,
str_field = (char *)entry + data_offset;

trace_seq_printf(s, print_fmt, se->fields[i]->name,
+ STR_VAR_LEN_MAX,
str_field,
i == se->n_fields - 1 ? "" : " ");
n_u64++;
} else {
trace_seq_printf(s, print_fmt, se->fields[i]->name,
+ STR_VAR_LEN_MAX,
(char *)&entry->fields[n_u64],
i == se->n_fields - 1 ? "" : " ");
n_u64 += STR_VAR_LEN_MAX / sizeof(u64);
--
2.17.1
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