From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 574976ABC for ; Fri, 1 Sep 2023 08:15:17 +0000 (UTC) Received: from ganesha.gnumonks.org (ganesha.gnumonks.org [IPv6:2001:780:45:1d:225:90ff:fe52:c662]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6A6048F; Fri, 1 Sep 2023 01:15:16 -0700 (PDT) Received: from [78.30.34.192] (port=39840 helo=gnumonks.org) by ganesha.gnumonks.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1qbzJ5-00AEiB-H4; Fri, 01 Sep 2023 10:15:10 +0200 Date: Fri, 1 Sep 2023 10:15:06 +0200 From: Pablo Neira Ayuso To: Jakub Kicinski Cc: joao@overdrivepizza.com, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kadlec@netfilter.org, fw@strlen.de, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, rkannoth@marvell.com, wojciech.drewek@intel.com, steen.hegenlund@microhip.com, keescook@chromium.org, Joao Moreira Subject: Re: [PATCH 0/2] Prevent potential write out of bounds Message-ID: References: <20230901010437.126631-1-joao@overdrivepizza.com> <20230831182800.25e5d4d9@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230831182800.25e5d4d9@kernel.org> X-Spam-Score: -1.9 (-) X-Spam-Status: No, score=-1.6 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On Thu, Aug 31, 2023 at 06:28:00PM -0700, Jakub Kicinski wrote: > On Thu, 31 Aug 2023 18:04:35 -0700 joao@overdrivepizza.com wrote: > > The function flow_rule_alloc in net/core/flow_offload.c [2] gets an > > unsigned int num_actions (line 10) and later traverses the actions in > > the rule (line 24) setting hw.stats to FLOW_ACTION_HW_STATS_DONT_CARE. > > > > Within the same file, the loop in the line 24 compares a signed int > > (i) to an unsigned int (num_actions), and then uses i as an array > > index. If an integer overflow happens, then the array within the loop > > is wrongly indexed, causing a write out of bounds. > > > > After checking with maintainers, it seems that the front-end caps the > > maximum value of num_action, thus it is not possible to reach the given > > write out of bounds, yet, still, to prevent disasters it is better to > > fix the signedness here. > > How did you find this? The commit messages should include info > about how the issue was discovered. This is net-next material IMO, none of the existing interfaces uses such a large number of actions for this to be an issue.