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| author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2026-06-04 18:23:35 -0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2026-06-05 17:19:31 -0300 |
| commit | 06e7994427ab56e32699a5e45d048ff0826f3d53 (patch) | |
| tree | 05d6af04d6db315cadfc96b0b2b82ff60ed7191f | |
| parent | fa20c1f8f4e094abe0169d39fce8181bc26d6dab (diff) | |
| download | linux-06e7994427ab56e32699a5e45d048ff0826f3d53.tar.gz linux-06e7994427ab56e32699a5e45d048ff0826f3d53.zip | |
perf sched: Cap max_cpu at MAX_CPUS in timehist sample processing
perf_timehist__process_sample() updates sched->max_cpu from the
sample CPU without bounds checking. Later code uses max_cpu + 1 as
an iteration count over arrays allocated with MAX_CPUS entries
(curr_thread, cpu_last_switched). A recording with CPU IDs >= MAX_CPUS
causes out-of-bounds array accesses.
Also cap the env->nr_cpus_online initialization of max_cpu in
perf_sched__timehist(), which could exceed MAX_CPUS on very large
systems.
Add bounds checks before both max_cpu updates, matching the pattern
already used in map_switch_event().
Fixes: 49394a2a24c7 ("perf sched timehist: Introduce timehist command")
Reviewed-by: David Ahern <dsahern@kernel.org>
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
| -rw-r--r-- | tools/perf/builtin-sched.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c index 7bd61028327b..87a1f4cf8760 100644 --- a/tools/perf/builtin-sched.c +++ b/tools/perf/builtin-sched.c @@ -3215,7 +3215,9 @@ static int perf_timehist__process_sample(const struct perf_tool *tool, .cpu = sample->cpu, }; - if (this_cpu.cpu > sched->max_cpu.cpu) + /* max_cpu indexes arrays allocated with MAX_CPUS entries */ + if (this_cpu.cpu >= 0 && this_cpu.cpu < MAX_CPUS && + this_cpu.cpu > sched->max_cpu.cpu) sched->max_cpu = this_cpu; if (evsel->handler != NULL) { @@ -3385,8 +3387,8 @@ static int perf_sched__timehist(struct perf_sched *sched) perf_session__set_tracepoints_handlers(session, migrate_handlers)) goto out; - /* pre-allocate struct for per-CPU idle stats */ - sched->max_cpu.cpu = env->nr_cpus_online; + /* pre-allocate struct for per-CPU idle stats; cap to array bounds */ + sched->max_cpu.cpu = min(env->nr_cpus_online, MAX_CPUS); if (sched->max_cpu.cpu == 0) sched->max_cpu.cpu = 4; if (init_idle_threads(sched->max_cpu.cpu)) |