From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f72.google.com (mail-pj1-f72.google.com [209.85.216.72]) (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 9F4D644C641 for ; Mon, 20 Jul 2026 17:55:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.72 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784570127; cv=none; b=rMCHznloEsPrAZJr4tTjwu/1NXJwknlRoixzNsAfSOtl+lCNeRM6UQTk/aTD2Yxmi/5xQRXEgSl6COK7+Q1lNt5XX7oPM75YIxaBSWZrfWaJZDCiG4qng2D3+9V0kSVOMAi4yM+hc4c0VwMqxIaGjzuQ2nsbGCnKBy2KFg54f2M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784570127; c=relaxed/simple; bh=3aX1EaAr1sbEmdIn9uz/KO4l+FvPsH+GN6jP8P1ep6A=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Content-Type; b=e6sEvs+qeDCm+6yMIBRnc7cseNNvfdZtuVHjuBa5DE9cKYWP6juPioBTBV2yz1uyPqnaFMOiJg3IbNeC5WexAlGojV4VQRZIQ74H8kLxzVW20LSzSzWCcskKAznesZJbuwfwNQU6lr8n+irLUyJx6mf4S1wlIHsmlgqLbRyLLZ0= 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=FVmNwouI; arc=none smtp.client-ip=209.85.216.72 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="FVmNwouI" Received: by mail-pj1-f72.google.com with SMTP id 98e67ed59e1d1-38e11baa66eso7482471a91.2 for ; Mon, 20 Jul 2026 10:55:20 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1784570118; x=1785174918; darn=vger.kernel.org; h=content-type:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=0RNdBnXJ5fF64ccDFnBustZkitp/xg6+f0zdlczyZFc=; b=FVmNwouIOiiv+j4iXpTvuHjBU/Hg/K+eeVJPXPNA9Ae12paQfo2w3lF4j6jRgJTJkd V56eJZ+ratMUZeWFD8R+SDOF3O5z2aoc4WUISBSoGSh7jGOrfoWA9n3ty5OLZ0suVvLd XW8tvzB5uqieSSQysDLJuAzlnskwqf98H/srox2zXUrZQdvAqqRoaJ6ly7gRouWsQw3v kAlw1sVmvCTIfzTxDMXVPB5NykGuukqhN/5FIyTHl1GvVm8HTLXoK4iLzwjvBnvyETo/ L6nGC9o3Ylmm3sr9eBw3SwJfqF89O9t/YDpIpjzanH0kvEzIn053cpPt+s47yVbAqHXb VvWw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784570118; x=1785174918; h=content-type:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=0RNdBnXJ5fF64ccDFnBustZkitp/xg6+f0zdlczyZFc=; b=PTXnUjAuvM6rIxm6FNGZSU9KBoh1Eib7dMXTgSxpFMHECQKxNuVYl7XkChM4g/yJW/ xUtH+SDFcJUdcbmHfIuE/omjh+QGK97OqSv17hiXd204L2LmrRP9oSJXEti8TqOY0PBp 2d7voHh/aEafVeiH+WO3ZNGHvKKlN130Wzh/Hnwjr2Yy4gyifRgw8eltoE0P2ja9MZgT wBjtiWdA1uFbpf6jq6xXsg5nkOzFEPYwJb1Mk5pOP6RgkqyD8VCJ/gP9hGegVFKHPkNr j9QwLOAaGb7F828+ubHQC19mQFGw05nauaUiDghsLqUiSid2aQJj1J0aTgmkOBX+Bkq9 9uPQ== X-Forwarded-Encrypted: i=1; AHgh+Ro3LTdyjPZ95KnN+Tdit7Cw0/QsV1brQzsbTRJyM58D7I3D4BQD18Twc6HCDrqS6MXESzVQOA7cLy4XLGI=@vger.kernel.org X-Gm-Message-State: AOJu0YyBgafMVpBWm0QZSsy7FKlF9H/BBSycc82U4wJgA0nAggLHdG6S um6PudPG0Y84d6R2aYNyGLIKftItfbG/ktLD8C2frZx/2ZIrF6UXZuOKByeTY+GOiZcTB6mZl5n LahT0lxWz3A== X-Received: from dlec16-n2.prod.google.com ([2002:a05:701b:4290:20b0:13c:ce0f:370f]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:4c46:b0:387:e0db:bc23 with SMTP id 98e67ed59e1d1-38e4b5536d4mr15288594a91.35.1784570117345; Mon, 20 Jul 2026 10:55:17 -0700 (PDT) Date: Mon, 20 Jul 2026 10:54:54 -0700 In-Reply-To: <20260720175455.3645946-1-irogers@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260720175455.3645946-1-irogers@google.com> X-Mailer: git-send-email 2.55.0.229.g6434b31f56-goog Message-ID: <20260720175455.3645946-4-irogers@google.com> Subject: [PATCH v1 3/4] perf synthetic-events: Fix bounds, stale state, and misc flags in kernel module synthesis From: Ian Rogers To: Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , Ravi Bangoria , Swapnil Sapkal , linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Fix potential buffer overruns in perf_event__synthesize_modules_maps_cb() by safely clamping long DSO names to the mmap/mmap2 filename boundaries. Explicitly assign and clear the misc flags and union padding across all iterations to prevent stale Build-ID state from leaking between module synthesis events. Assisted-by: Antigravity:gemini-3.5-flash Signed-off-by: Ian Rogers --- tools/perf/util/synthetic-events.c | 70 +++++++++++++++++++++--------- 1 file changed, 50 insertions(+), 20 deletions(-) diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c index 9161dc728e6e..aab958cb3bc5 100644 --- a/tools/perf/util/synthetic-events.c +++ b/tools/perf/util/synthetic-events.c @@ -748,6 +748,7 @@ struct perf_event__synthesize_modules_maps_cb_args { perf_event__handler_t process; struct machine *machine; union perf_event *event; + u16 misc; }; static int perf_event__synthesize_modules_maps_cb(struct map *map, void *data) @@ -755,49 +756,78 @@ static int perf_event__synthesize_modules_maps_cb(struct map *map, void *data) struct perf_event__synthesize_modules_maps_cb_args *args = data; union perf_event *event = args->event; struct dso *dso; - size_t size; + size_t size, aligned_size; + int rc = 0; if (!__map__is_kmodule(map)) return 0; dso = map__dso(map); if (!symbol_conf.no_buildid_mmap2) { - size = PERF_ALIGN(dso__long_name_len(dso) + 1, sizeof(u64)); + const char *long_name = dso__long_name(dso); + + size = strlen(long_name); + if (size >= sizeof(event->mmap2.filename)) + size = sizeof(event->mmap2.filename) - 1; + + strlcpy(event->mmap2.filename, long_name, + sizeof(event->mmap2.filename)); + + aligned_size = PERF_ALIGN(size + 1, sizeof(u64)); event->mmap2.header.type = PERF_RECORD_MMAP2; - event->mmap2.header.size = (sizeof(event->mmap2) - - (sizeof(event->mmap2.filename) - size)); - memset(event->mmap2.filename + size, 0, args->machine->id_hdr_size); + event->mmap2.header.misc = args->misc; + event->mmap2.header.size = + offsetof(struct perf_record_mmap2, filename) + + aligned_size; + + /* Zero the padding and ID header trailer safely! */ + memset(event->mmap2.filename + size, 0, + (aligned_size - size) + args->machine->id_hdr_size); + event->mmap2.header.size += args->machine->id_hdr_size; event->mmap2.start = map__start(map); event->mmap2.len = map__size(map); event->mmap2.pid = args->machine->pid; - memcpy(event->mmap2.filename, dso__long_name(dso), dso__long_name_len(dso) + 1); - - /* Clear stale build ID from previous module iteration */ + /* Clear stale build ID and entire union from previous module iteration */ event->mmap2.header.misc &= ~PERF_RECORD_MISC_MMAP_BUILD_ID; memset(event->mmap2.build_id, 0, sizeof(event->mmap2.build_id)); event->mmap2.build_id_size = 0; + event->mmap2.__reserved_1 = 0; + event->mmap2.__reserved_2 = 0; perf_record_mmap2__read_build_id(&event->mmap2, args->machine, false); } else { - size = PERF_ALIGN(dso__long_name_len(dso) + 1, sizeof(u64)); + const char *long_name = dso__long_name(dso); + + size = strlen(long_name); + if (size >= sizeof(event->mmap.filename)) + size = sizeof(event->mmap.filename) - 1; + + strlcpy(event->mmap.filename, long_name, + sizeof(event->mmap.filename)); + + aligned_size = PERF_ALIGN(size + 1, sizeof(u64)); event->mmap.header.type = PERF_RECORD_MMAP; - event->mmap.header.size = (sizeof(event->mmap) - - (sizeof(event->mmap.filename) - size)); - memset(event->mmap.filename + size, 0, args->machine->id_hdr_size); + event->mmap.header.misc = args->misc; + event->mmap.header.size = + offsetof(struct perf_record_mmap, filename) + + aligned_size; + + /* Zero the padding and ID header trailer safely! */ + memset(event->mmap.filename + size, 0, + (aligned_size - size) + args->machine->id_hdr_size); + event->mmap.header.size += args->machine->id_hdr_size; event->mmap.start = map__start(map); event->mmap.len = map__size(map); event->mmap.pid = args->machine->pid; - - memcpy(event->mmap.filename, dso__long_name(dso), dso__long_name_len(dso) + 1); } if (perf_tool__process_synth_event(args->tool, event, args->machine, args->process) != 0) - return -1; + rc = -1; - return 0; + return rc; } int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__handler_t process, @@ -822,13 +852,13 @@ int perf_event__synthesize_modules(const struct perf_tool *tool, perf_event__han } /* - * kernel uses 0 for user space maps, see kernel/perf_event.c - * __perf_event_mmap + * Just like the kernel, see perf_misc_flags() in + * kernel/events/core.c */ if (machine__is_host(machine)) - args.event->header.misc = PERF_RECORD_MISC_KERNEL; + args.misc = PERF_RECORD_MISC_KERNEL; else - args.event->header.misc = PERF_RECORD_MISC_GUEST_KERNEL; + args.misc = PERF_RECORD_MISC_GUEST_KERNEL; rc = maps__for_each_map(maps, perf_event__synthesize_modules_maps_cb, &args); -- 2.55.0.229.g6434b31f56-goog