Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 31 Aug 2023 18:28:00 -0700
From:   Jakub Kicinski <kuba@kernel.org>
To:     joao@overdrivepizza.com
Cc:     pablo@netfilter.org, 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 <joao.moreira@intel.com>
Subject: Re: [PATCH 0/2] Prevent potential write out of bounds
Message-ID: <20230831182800.25e5d4d9@kernel.org>
In-Reply-To: <20230901010437.126631-1-joao@overdrivepizza.com>
References: <20230901010437.126631-1-joao@overdrivepizza.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Precedence: bulk

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.
-- 
pw-bot: cr