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=-19.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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 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 9736FC43461 for ; Mon, 17 May 2021 15:27:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7EC876101E for ; Mon, 17 May 2021 15:27:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244356AbhEQP2m (ORCPT ); Mon, 17 May 2021 11:28:42 -0400 Received: from mail.kernel.org ([198.145.29.99]:36458 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243513AbhEQPOP (ORCPT ); Mon, 17 May 2021 11:14:15 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8DBEF61C51; Mon, 17 May 2021 14:32:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621261921; bh=G5ssfBGRLK53uQMuqh6icA54W4r/oxerTpHLqKs707Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XXOU5ZD6dl9BRgsHUNcEJlbQ/6tzrx1LhdXqeEV5+EluvAt52CseeIlzzVGh+LMZr YYbvTF4far2B2P1QY4MwwVDx4vGlpxiVLP5U2mhwTWaOZwnkuuLeLtdUNWhwMlUBeb EwhOPsCBy/dn7bNx6leUVuZWA0CjMpvZ5Fwmanlc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Brendan Jackman , Andrii Nakryiko , Sasha Levin Subject: [PATCH 5.11 187/329] libbpf: Fix signed overflow in ringbuf_process_ring Date: Mon, 17 May 2021 16:01:38 +0200 Message-Id: <20210517140308.452003031@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210517140302.043055203@linuxfoundation.org> References: <20210517140302.043055203@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Brendan Jackman [ Upstream commit 2a30f9440640c418bcfbea9b2b344d268b58e0a2 ] One of our benchmarks running in (Google-internal) CI pushes data through the ringbuf faster htan than userspace is able to consume it. In this case it seems we're actually able to get >INT_MAX entries in a single ring_buffer__consume() call. ASAN detected that cnt overflows in this case. Fix by using 64-bit counter internally and then capping the result to INT_MAX before converting to the int return type. Do the same for the ring_buffer__poll(). Fixes: bf99c936f947 (libbpf: Add BPF ring buffer support) Signed-off-by: Brendan Jackman Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20210429130510.1621665-1-jackmanb@google.com Signed-off-by: Sasha Levin --- tools/lib/bpf/ringbuf.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-) diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c index e7a8d847161f..1d80ad4e0de8 100644 --- a/tools/lib/bpf/ringbuf.c +++ b/tools/lib/bpf/ringbuf.c @@ -202,9 +202,11 @@ static inline int roundup_len(__u32 len) return (len + 7) / 8 * 8; } -static int ringbuf_process_ring(struct ring* r) +static int64_t ringbuf_process_ring(struct ring* r) { - int *len_ptr, len, err, cnt = 0; + int *len_ptr, len, err; + /* 64-bit to avoid overflow in case of extreme application behavior */ + int64_t cnt = 0; unsigned long cons_pos, prod_pos; bool got_new_data; void *sample; @@ -244,12 +246,14 @@ done: } /* Consume available ring buffer(s) data without event polling. - * Returns number of records consumed across all registered ring buffers, or - * negative number if any of the callbacks return error. + * Returns number of records consumed across all registered ring buffers (or + * INT_MAX, whichever is less), or negative number if any of the callbacks + * return error. */ int ring_buffer__consume(struct ring_buffer *rb) { - int i, err, res = 0; + int64_t err, res = 0; + int i; for (i = 0; i < rb->ring_cnt; i++) { struct ring *ring = &rb->rings[i]; @@ -259,18 +263,24 @@ int ring_buffer__consume(struct ring_buffer *rb) return err; res += err; } + if (res > INT_MAX) + return INT_MAX; return res; } /* Poll for available data and consume records, if any are available. - * Returns number of records consumed, or negative number, if any of the - * registered callbacks returned error. + * Returns number of records consumed (or INT_MAX, whichever is less), or + * negative number, if any of the registered callbacks returned error. */ int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms) { - int i, cnt, err, res = 0; + int i, cnt; + int64_t err, res = 0; cnt = epoll_wait(rb->epoll_fd, rb->events, rb->ring_cnt, timeout_ms); + if (cnt < 0) + return -errno; + for (i = 0; i < cnt; i++) { __u32 ring_id = rb->events[i].data.fd; struct ring *ring = &rb->rings[ring_id]; @@ -280,7 +290,9 @@ int ring_buffer__poll(struct ring_buffer *rb, int timeout_ms) return err; res += err; } - return cnt < 0 ? -errno : res; + if (res > INT_MAX) + return INT_MAX; + return res; } /* Get an fd that can be used to sleep until data is available in the ring(s) */ -- 2.30.2