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perf sched: Replace BUG_ON on invalid CPU with graceful skip

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latency_switch_event(), latency_runtime_event(), and map_switch_event()
use BUG_ON(cpu >= MAX_CPUS || cpu < 0) to validate the sample CPU.
When PERF_SAMPLE_CPU is absent from the sample type,
evsel__parse_sample() initializes sample->cpu to (u32)-1.  Casting
this to int yields -1, which triggers the BUG_ON and aborts perf sched.

The central CPU validation in perf_session__deliver_event() intentionally
preserves the (u32)-1 sentinel for downstream tools like perf script
and perf inject, so leaf callbacks must handle it themselves.

Replace the three BUG_ON calls with graceful skips using pr_warning(),
matching the existing pattern in process_sched_switch_event() and
process_sched_runtime_event() earlier in the same file.  Include the
file offset for cross-referencing with perf report -D.

Reported-by: sashiko-bot@kernel.org # Running on a local machine
Reviewed-by: Ian Rogers <irogers@google.com>
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2026-06-01 19:53:41 -03:00
parent fa06520fa0
commit 1e2c83f732
1 changed files with 19 additions and 3 deletions
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22
tools/perf/builtin-sched.c
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@ -1145,7 +1145,12 @@ static int latency_switch_event(struct perf_sched *sched,
int cpu = sample->cpu, err = -1;
s64 delta;
BUG_ON(cpu >= MAX_CPUS || cpu < 0);
/* perf.data is untrusted input — CPU may be absent or corrupted */
if (cpu >= MAX_CPUS || cpu < 0) {
pr_warning("WARNING: at offset %#" PRIx64 ": out-of-bound sample CPU %d, skipping sample\n",
sample->file_offset, cpu);
return 0;
}
timestamp0 = sched->cpu_last_switched[cpu];
sched->cpu_last_switched[cpu] = timestamp;
@ -1215,7 +1220,13 @@ static int latency_runtime_event(struct perf_sched *sched,
if (thread == NULL)
return -1;
BUG_ON(cpu >= MAX_CPUS || cpu < 0);
/* perf.data is untrusted input — CPU may be absent or corrupted */
if (cpu >= MAX_CPUS || cpu < 0) {
pr_warning("WARNING: at offset %#" PRIx64 ": out-of-bound sample CPU %d, skipping sample\n",
sample->file_offset, cpu);
err = 0;
goto out_put;
}
if (!atoms) {
if (thread_atoms_insert(sched, thread))
goto out_put;
@ -1640,7 +1651,12 @@ static int map_switch_event(struct perf_sched *sched, struct perf_sample *sampl
const char *str;
int ret = -1;
BUG_ON(this_cpu.cpu >= MAX_CPUS || this_cpu.cpu < 0);
/* perf.data is untrusted input — CPU may be absent or corrupted */
if (this_cpu.cpu >= MAX_CPUS || this_cpu.cpu < 0) {
pr_warning("WARNING: at offset %#" PRIx64 ": out-of-bound sample CPU %d, skipping sample\n",
sample->file_offset, this_cpu.cpu);
return 0;
}
if (this_cpu.cpu > sched->max_cpu.cpu)
sched->max_cpu = this_cpu;