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perf timechart: Fix memory leaks

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Resolve a major execution-time leak of backtrace strings in the timechart tool.

- Modify cat_backtrace() to return dynamically allocated memory via
  open_memstream(), transferring ownership to the caller.
- Free the returned backtrace string inside process_sample_event() immediately
  after invoking the tracepoint handler.
- In handlers like pid_put_sample() and sched_wakeup(), make a separate copy of
  the backtrace using strdup() if it needs to be persisted in the sample struct,
  preventing lifetime issues and double-free vulnerabilities.

Signed-off-by: Ian Rogers <irogers@google.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrew Jones <ajones@ventanamicro.com>
Cc: Anup Patel <anup@brainfault.org>
Cc: Athira Rajeev <atrajeev@linux.ibm.com>
Cc: Blake Jones <blakejones@google.com>
Cc: Chen Ni <nichen@iscas.ac.cn>
Cc: Chun-Tse Shao <ctshao@google.com>
Cc: Dapeng Mi <dapeng1.mi@linux.intel.com>
Cc: Derek Foreman <derek.foreman@collabora.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Dr. David Alan Gilbert <linux@treblig.org>
Cc: Howard Chu <howardchu95@gmail.com>
Cc: Hrishikesh Suresh <hrishikesh123s@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Krzysztof Łopatowski <krzysztof.m.lopatowski@gmail.com>
Cc: Leo Yan <leo.yan@arm.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quan Zhou <zhouquan@iscas.ac.cn>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Swapnil Sapkal <swapnil.sapkal@amd.com>
Cc: Thomas Falcon <thomas.falcon@intel.com>
Cc: Tianyou Li <tianyou.li@intel.com>
Cc: Yujie Liu <yujie.liu@intel.com>
Cc: tanze <tanze@kylinos.cn>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Ian Rogers 2026-05-20 12:05:30 -07:00 committed by Arnaldo Carvalho de Melo
parent 8dca7ad2c2
commit 00b36b394c
1 changed files with 10 additions and 7 deletions
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17
tools/perf/builtin-timechart.c
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@ -299,7 +299,7 @@ static void pid_put_sample(struct timechart *tchart, int pid, int type,
sample->type = type;
sample->next = c->samples;
sample->cpu = cpu;
sample->backtrace = backtrace;
sample->backtrace = backtrace ? strdup(backtrace) : NULL;
c->samples = sample;
if (sample->type == TYPE_RUNNING && end > start && start > 0) {
@ -433,7 +433,7 @@ static void sched_wakeup(struct timechart *tchart, int cpu, u64 timestamp,
we->time = timestamp;
we->waker = waker;
we->backtrace = backtrace;
we->backtrace = backtrace ? strdup(backtrace) : NULL;
if ((flags & TRACE_FLAG_HARDIRQ) || (flags & TRACE_FLAG_SOFTIRQ))
we->waker = -1;
@ -489,9 +489,9 @@ static void sched_switch(struct timechart *tchart, int cpu, u64 timestamp,
}
}
static const char *cat_backtrace(union perf_event *event,
struct perf_sample *sample,
struct machine *machine)
static char *cat_backtrace(union perf_event *event,
struct perf_sample *sample,
struct machine *machine)
{
struct addr_location al;
unsigned int i;
@ -577,6 +577,7 @@ static int process_sample_event(const struct perf_tool *tool,
{
struct timechart *tchart = container_of(tool, struct timechart, tool);
struct evsel *evsel = sample->evsel;
int ret = 0;
if (evsel->core.attr.sample_type & PERF_SAMPLE_TIME) {
if (!tchart->first_time || tchart->first_time > sample->time)
@ -587,11 +588,13 @@ static int process_sample_event(const struct perf_tool *tool,
if (evsel->handler != NULL) {
tracepoint_handler f = evsel->handler;
char *backtrace = cat_backtrace(event, sample, machine);
return f(tchart, sample, cat_backtrace(event, sample, machine));
ret = f(tchart, sample, backtrace);
free(backtrace);
}
return 0;
return ret;
}
static int