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tracing: Check for printable characters when printing field dyn strings

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When the "fields" option is enabled, it prints each trace event field
based on its type. But a dynamic array and a dynamic string can both have
a "char *" type. Printing it as a string can cause escape characters to be
printed and mess up the output of the trace.

For dynamic strings, test if there are any non-printable characters, and
if so, print both the string with the non printable characters as '.', and
the print the hex value of the array.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Takaya Saeki <takayas@google.com>
Cc: Tom Zanussi <zanussi@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ian Rogers <irogers@google.com>
Cc: Douglas Raillard <douglas.raillard@arm.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Link: https://lore.kernel.org/20251028231148.929243047@kernel.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2025-10-28 19:11:26 -04:00 committed by Steven Rostedt (Google)
parent 64b627c8da
commit b6e5d971fc
1 changed files with 25 additions and 2 deletions
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27
kernel/trace/trace_output.c
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@ -950,7 +950,9 @@ static void print_fields(struct trace_iterator *iter, struct trace_event_call *c
int offset;
int len;
int ret;
int i;
void *pos;
char *str;
list_for_each_entry_reverse(field, head, link) {
trace_seq_printf(&iter->seq, " %s=", field->name);
@ -977,8 +979,29 @@ static void print_fields(struct trace_iterator *iter, struct trace_event_call *c
trace_seq_puts(&iter->seq, "<OVERFLOW>");
break;
}
pos = (void *)iter->ent + offset;
trace_seq_printf(&iter->seq, "%.*s", len, (char *)pos);
str = (char *)iter->ent + offset;
/* Check if there's any non printable strings */
for (i = 0; i < len; i++) {
if (str[i] && !(isascii(str[i]) && isprint(str[i])))
break;
}
if (i < len) {
for (i = 0; i < len; i++) {
if (isascii(str[i]) && isprint(str[i]))
trace_seq_putc(&iter->seq, str[i]);
else
trace_seq_putc(&iter->seq, '.');
}
trace_seq_puts(&iter->seq, " (");
for (i = 0; i < len; i++) {
if (i)
trace_seq_putc(&iter->seq, ':');
trace_seq_printf(&iter->seq, "%02x", str[i]);
}
trace_seq_putc(&iter->seq, ')');
} else {
trace_seq_printf(&iter->seq, "%.*s", len, str);
}
break;
case FILTER_PTR_STRING:
if (!iter->fmt_size)