From nobody Thu Oct 2 16:30:54 2025 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 507EB42A96 for ; Sun, 14 Sep 2025 18:33:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757874840; cv=none; b=k75bXW0Hce9ZaGkhuvtLa3GtBGbamdM4i4TuLA7BdnRvUaNbduGdxCWYsBn5Rycnlqw6X4PKujzBg77eH8lURj8H9JDxotO+P5MMDrTxBw6oy4mzwGxubH5FkRkaD7Gr4bcwOCJars9J1xwYi+IfEbSJJMPwdp4+L9UMwjPbG9s= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757874840; c=relaxed/simple; bh=dmBpq3/7O/v41r+GDh+rnnlXPTGB3FAZAyg8cX0y2xw=; h=Date:Mime-Version:Message-ID:Subject:From:To:Content-Type; b=QOa1jKeq6l0wW4SrqA+YHIQk8x5KWrEL4tVBAzLosqvB5Ic5+/5tm1Vbzq+NU23JwuZ1K8OPf75tPwe/Ysvgak5OzbCRqVfTFRbYCBUkXmU+QvoNsJAUlBMoc5uPBQeaq4TS0OAJKnHWQVyuupTT9fxoiVJ5X+xV9JXokbg5l0s= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=tvnIkiOP; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="tvnIkiOP" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-2507ae2fa99so65831025ad.1 for ; Sun, 14 Sep 2025 11:33:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1757874838; x=1758479638; darn=vger.kernel.org; h=to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=wN2iccbVuVBwktRQK01qZKdZc7wUELk9NMoe4QbKLb8=; b=tvnIkiOPQlZ0+J2taqiJ19RVylVtaBSwRtVHFbWDENDa3vVsycGkAhM9CQCPjbyQJH d75/YTw+LZm/En8iBpXHRJqto2illYNmi6GfNX+UYJYkZtTORVrsxaGIORzr2UE4q7KC DjQ+QztOie+S03YI2az2R0ODmClS+DDxj6XqPwm5Azobr2SCnM0p3owSP3PwKgjo+5Dr AVUqYK8kGcT7pEKoK1cEslQl2KuB6F1DZr2WeyLx92Oqlz/YD5qLtr96cifJoWl8fOv6 RsUCmfLE2lccr7Y37DHIwiYCJyf/hmIFdOt69XtzETpEl3zhCETFoxB+vO74qAmWxLVv S/Nw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1757874838; x=1758479638; h=to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=wN2iccbVuVBwktRQK01qZKdZc7wUELk9NMoe4QbKLb8=; b=HJ4RfTm8FW63oGooIa9R8Wo+6Ubyne9YHPDjepXlGby2nPWjTu7zPzW+fGPD/kCqOw iMhYZrM1HU/Y5HAsrTyfQk1oDk8eGWt8M1fd1KdwVlqunraxqBnnivY3nilvhfA8j7pe Twjs2vxbCD7wYfBA0c0lh4OuTEAKhlxif2vClQXNylVNzr6AyRQG/b6MIFZ2uom1QJeP HxesIbV6bqEP4IiM+DWF/alpNgA4acynbKFuDLk8JNGKOLKjSMaFEmvyi2n+rdx7STP4 EX7wlqCPY+cLzAcrQmW1Dfqltu74nnoXdu9hmq4ddZ5AxrwZnIsYb1Tf5bMh9NizF14r 0Kmg== X-Forwarded-Encrypted: i=1; AJvYcCXnqos2sbffWvsvJAObS5Ecs+iKJE7lZJvv1BMn+6XyHVgOUqsGGmD+EGqglge5r+sSaBH8X7fgv1dQZYc=@vger.kernel.org X-Gm-Message-State: AOJu0YwezbLwR6VGaTajRQoih/q00Vi2lEILQX8VV+ybtRpq7rl2eHca lTYMJMnQ8hhm/zcH6CTGskZKd266s3fkpbe1Kmh88uMBVLYm5r2ALKw6qSgbxilp5+0j5fYqM1S z1hZGbwqDFg== X-Google-Smtp-Source: AGHT+IF5F7RkNRcG5yv3XsFGcxWPT1s6w1jEj6xSWNSgWac2TDVnOvfsv/01vPbaqPE58WtPgrCmaFZ8kLx3 X-Received: from plkh5.prod.google.com ([2002:a17:903:19e5:b0:24b:12ba:f799]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:1aa4:b0:24b:15b3:223d with SMTP id d9443c01a7336-25d24da6cf9mr129138075ad.16.1757874838626; Sun, 14 Sep 2025 11:33:58 -0700 (PDT) Date: Sun, 14 Sep 2025 11:33:53 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.51.0.384.g4c02a37b29-goog Message-ID: <20250914183353.1962899-1-irogers@google.com> Subject: [PATCH v1] perf sched: Avoid union type punning undefined behavior From: Ian Rogers To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , Kan Liang , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" A union is used to set the priv value in thread (a void*) to a boolean value through type punning. Undefined behavior sanitizer fails on this. Signed-off-by: Ian Rogers --- tools/perf/builtin-sched.c | 19 ++++--------------- 1 file changed, 4 insertions(+), 15 deletions(-) diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c index f166d6cbc083..eca3b1c58c4b 100644 --- a/tools/perf/builtin-sched.c +++ b/tools/perf/builtin-sched.c @@ -1532,35 +1532,24 @@ static int process_sched_wakeup_ignore(const struct= perf_tool *tool __maybe_unus return 0; } =20 -union map_priv { - void *ptr; - bool color; -}; - static bool thread__has_color(struct thread *thread) { - union map_priv priv =3D { - .ptr =3D thread__priv(thread), - }; - - return priv.color; + return thread__priv(thread) !=3D NULL; } =20 static struct thread* map__findnew_thread(struct perf_sched *sched, struct machine *machine, pid= _t pid, pid_t tid) { struct thread *thread =3D machine__findnew_thread(machine, pid, tid); - union map_priv priv =3D { - .color =3D false, - }; + bool color =3D false; =20 if (!sched->map.color_pids || !thread || thread__priv(thread)) return thread; =20 if (thread_map__has(sched->map.color_pids, tid)) - priv.color =3D true; + color =3D true; =20 - thread__set_priv(thread, priv.ptr); + thread__set_priv(thread, color ? ((void*)1) : NULL); return thread; } =20 --=20 2.51.0.384.g4c02a37b29-goog