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perf sched: Fix NULL dereference in latency_runtime_event

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latency_runtime_event() passes the return value of
machine__findnew_thread() directly to thread_atoms_search() at line
1216, before checking for NULL at line 1220.  thread_atoms_search()
calls pid_cmp() which dereferences the thread pointer via
thread__tid(), causing a NULL pointer dereference if the allocation
fails.

All other callers of thread_atoms_search() in this file
(latency_switch_event, latency_wakeup_event,
latency_migrate_task_event) correctly check for NULL first.

Move the atoms assignment after the NULL check to match the pattern
used by the other callers.

Fixes: b91fc39f4a ("perf machine: Protect the machine->threads with a rwlock")
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>
This commit is contained in:
Arnaldo Carvalho de Melo 2026-06-04 12:56:02 -03:00
parent 66ea9de603
commit 8cbca8a480
1 changed files with 3 additions and 1 deletions
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4
tools/perf/builtin-sched.c
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@ -1213,13 +1213,15 @@ static int latency_runtime_event(struct perf_sched *sched,
const u32 pid = perf_sample__intval(sample, "pid");
const u64 runtime = perf_sample__intval(sample, "runtime");
struct thread *thread = machine__findnew_thread(machine, -1, pid);
struct work_atoms *atoms = thread_atoms_search(&sched->atom_root, thread, &sched->cmp_pid);
struct work_atoms *atoms;
u64 timestamp = sample->time;
int cpu = sample->cpu, err = -1;
if (thread == NULL)
return -1;
atoms = thread_atoms_search(&sched->atom_root, thread, &sched->cmp_pid);
/* 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",