From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7088DC433ED for ; Tue, 27 Apr 2021 17:09:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 43CE061289 for ; Tue, 27 Apr 2021 17:09:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236627AbhD0RKW (ORCPT ); Tue, 27 Apr 2021 13:10:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34282 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235512AbhD0RKR (ORCPT ); Tue, 27 Apr 2021 13:10:17 -0400 Received: from mail-wr1-x449.google.com (mail-wr1-x449.google.com [IPv6:2a00:1450:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9CBBC061756 for ; Tue, 27 Apr 2021 10:09:31 -0700 (PDT) Received: by mail-wr1-x449.google.com with SMTP id 65-20020adf82c70000b0290107593a42c3so9413412wrc.5 for ; Tue, 27 Apr 2021 10:09:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=mu8pX+qKetUtW12TmI9eJNbJjh/oUdlMUUsluEXLfvw=; b=WCpOjzlkH6FzzoyCziZGd4rXEDGbXBj/lLhRUgVLmERfRaWHFdc+72dNdyUlitF6ya Nh8THY92dUXL/RvjEgqfQZ9SErCn8xmPd3WWoYF+5/4Rra53oi45hgR/ApWgIePwMj55 ysdigqlMn0S1XDUQBMGGBjgKFgl4WU13YwTB3jrJ62wP35NPLYqeb0tZ75jA0bTU1xLw DCiMn9dWs10Ozf9ohr0Ciwl4AFL37PuqEvcTkXuXcrRVdmsvTXuX1P/7hgR83jRv9f3x rv8y0fNjNI53NJp90tYLcd4w+M1F8i4BUZrlucc/19+VxwtTC5OuMonAPcACXvOsshed ArNA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=mu8pX+qKetUtW12TmI9eJNbJjh/oUdlMUUsluEXLfvw=; b=HR4rpJSZxdpCxRhOZpUqyRdquVLJDQ4XtKnl0xPZp+cMVsYh1Dpc//OiGkPXtPVHQz WRKUMJSem+7skxfNiYhfQKMw7AqptuyB/6zfp5s/O7Ocxzb8bS/tF5oCodGZ6CgOhEdn fOx8oCvOrLypg7GIiTx39GM7pkLQ7DWYgjG6EikXAgGKzYROuDv/Gq0xQECM6jWat7eN UAQEYH5e5K2MbUr1X52R4LFZRCMITZ735XFxdP9lH746Tsgqy0k4MJ38Zj1cbBrvImBe mCWhG9zbTmro4qok0Emlg8Qvy7yQnfIQuQQljquZfxPVV+tcJEaF53hPL9shW/ETqerS VXIg== X-Gm-Message-State: AOAM5329TIzJxD0znkGERxB3ccxGS/oZjfILstT4+Ap6yS4yusyG6zGc yCAAUr0KgekD26iHTrgwu2OXJXVEnPJZJA== X-Google-Smtp-Source: ABdhPJyefHhcmwYReiM2A2TwzgIWtD0xJux9CmXCPPb97LV9WTjsEUBW+WDFYB4DSs6Bi2ggVQYpKTRblq6tYg== X-Received: from beeg.c.googlers.com ([fda3:e722:ac3:10:28:9cb1:c0a8:11db]) (user=jackmanb job=sendgmr) by 2002:a7b:c5c1:: with SMTP id n1mr5257391wmk.83.1619543369004; Tue, 27 Apr 2021 10:09:29 -0700 (PDT) Date: Tue, 27 Apr 2021 17:08:59 +0000 Message-Id: <20210427170859.579924-1-jackmanb@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.31.1.498.g6c1eba8ee3d-goog Subject: [PATCH bpf-next] libbpf: Fix signed overflow in ringbuf_process_ring From: Brendan Jackman To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, linux-kernel@vger.kernel.org, Brendan Jackman Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org One of our benchmarks running in (Google-internal) CI pushes data through the ringbuf faster than userspace is able to consume it. In this case it seems we're actually able to get >INT_MAX entries in a single ringbuf_buffer__consume call. ASAN detected that cnt overflows in this case. Fix by just setting a limit on the number of entries that can be consumed. Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support) Signed-off-by: Brendan Jackman --- tools/lib/bpf/ringbuf.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c index e7a8d847161f..445a21df0934 100644 --- a/tools/lib/bpf/ringbuf.c +++ b/tools/lib/bpf/ringbuf.c @@ -213,8 +213,8 @@ static int ringbuf_process_ring(struct ring* r) do { got_new_data = false; prod_pos = smp_load_acquire(r->producer_pos); - while (cons_pos < prod_pos) { + /* Don't read more than INT_MAX, or the return vale won't make sense. */ + while (cons_pos < prod_pos && cnt < INT_MAX) { len_ptr = r->data + (cons_pos & r->mask); len = smp_load_acquire(len_ptr); -- 2.31.1.498.g6c1eba8ee3d-goog