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=-19.4 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 0F7EDC2B9F6 for ; Wed, 12 May 2021 19:23:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D79E9613F7 for ; Wed, 12 May 2021 19:23:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1379653AbhELTUG (ORCPT ); Wed, 12 May 2021 15:20:06 -0400 Received: from mail.kernel.org ([198.145.29.99]:43882 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244733AbhELQvI (ORCPT ); Wed, 12 May 2021 12:51:08 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 6861361C86; Wed, 12 May 2021 16:17:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620836255; bh=iL9F0uU2nkg5CIRC/Gc/9Qbk5I/M2tuzeiAsq5MVDQM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1oB3iDnGSYzEBh1pK1huXMTJ4g+77fnf1X1LzPmrSPLUAkQpHVKNjOxvJWDhrlsKq YQmcwMoi6LunktX9xnaoLKbluqyTPm1wR/n1rSBrd7UsfFWvLwZAGve2hklRUt84wf AVxMdbrxxQTqo+NXOfr+7tryNNGLJ4kYzka+gaUg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thadeu Lima de Souza Cascardo , Daniel Borkmann , Andrii Nakryiko , Alexei Starovoitov Subject: [PATCH 5.12 672/677] bpf, ringbuf: Deny reserve of buffers larger than ringbuf Date: Wed, 12 May 2021 16:51:58 +0200 Message-Id: <20210512144859.685292990@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512144837.204217980@linuxfoundation.org> References: <20210512144837.204217980@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: Thadeu Lima de Souza Cascardo commit 4b81ccebaeee885ab1aa1438133f2991e3a2b6ea upstream. A BPF program might try to reserve a buffer larger than the ringbuf size. If the consumer pointer is way ahead of the producer, that would be successfully reserved, allowing the BPF program to read or write out of the ringbuf allocated area. Reported-by: Ryota Shiga (Flatt Security) Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it") Signed-off-by: Thadeu Lima de Souza Cascardo Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/ringbuf.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/bpf/ringbuf.c +++ b/kernel/bpf/ringbuf.c @@ -315,6 +315,9 @@ static void *__bpf_ringbuf_reserve(struc return NULL; len = round_up(size + BPF_RINGBUF_HDR_SZ, 8); + if (len > rb->mask + 1) + return NULL; + cons_pos = smp_load_acquire(&rb->consumer_pos); if (in_nmi()) {