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=-19.0 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, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 CD7F0C433E0 for ; Mon, 22 Mar 2021 13:00:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8D80619A2 for ; Mon, 22 Mar 2021 13:00:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231339AbhCVM7w (ORCPT ); Mon, 22 Mar 2021 08:59:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:49508 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230482AbhCVM4Y (ORCPT ); Mon, 22 Mar 2021 08:56:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 184B5619BC; Mon, 22 Mar 2021 12:48:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1616417309; bh=EDHo5EtwE/zUEs+4jbe7lpalNHcGSxojzeaT9hy/QTc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2rtrO0+gOllaXjh6c9YfgNMrT7pnqeTJfJsaw5sGOCBA3uFm0B17oAXvd71VTS9OI SxrQK7mx3GUrV4zVazmb3VaRy37WQyd4EtzNQMldhEwP5B97hEtFsfHtNwui3nxcBh 2vdaWaID+mkcBbGv1w1IFmY9DDbkk8jA7gizNhmg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Piotr Krysiuk , Daniel Borkmann , Alexei Starovoitov Subject: [PATCH 4.14 06/43] bpf: Add sanity check for upper ptr_limit Date: Mon, 22 Mar 2021 13:28:47 +0100 Message-Id: <20210322121920.260131229@linuxfoundation.org> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20210322121920.053255560@linuxfoundation.org> References: <20210322121920.053255560@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: stable@vger.kernel.org From: Piotr Krysiuk commit 1b1597e64e1a610c7a96710fc4717158e98a08b3 upstream. Given we know the max possible value of ptr_limit at the time of retrieving the latter, add basic assertions, so that the verifier can bail out if anything looks odd and reject the program. Nothing triggered this so far, but it also does not hurt to have these. Signed-off-by: Piotr Krysiuk Co-developed-by: Daniel Borkmann Signed-off-by: Daniel Borkmann Acked-by: Alexei Starovoitov Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/verifier.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2029,24 +2029,29 @@ static int retrieve_ptr_limit(const stru { bool mask_to_left = (opcode == BPF_ADD && off_is_neg) || (opcode == BPF_SUB && !off_is_neg); - u32 off; + u32 off, max; switch (ptr_reg->type) { case PTR_TO_STACK: + /* Offset 0 is out-of-bounds, but acceptable start for the + * left direction, see BPF_REG_FP. + */ + max = MAX_BPF_STACK + mask_to_left; off = ptr_reg->off + ptr_reg->var_off.value; if (mask_to_left) *ptr_limit = MAX_BPF_STACK + off; else *ptr_limit = -off - 1; - return 0; + return *ptr_limit >= max ? -ERANGE : 0; case PTR_TO_MAP_VALUE: + max = ptr_reg->map_ptr->value_size; if (mask_to_left) { *ptr_limit = ptr_reg->umax_value + ptr_reg->off; } else { off = ptr_reg->smin_value + ptr_reg->off; *ptr_limit = ptr_reg->map_ptr->value_size - off - 1; } - return 0; + return *ptr_limit >= max ? -ERANGE : 0; default: return -EINVAL; }