From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 C919915666A; Thu, 29 Aug 2024 09:06:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724922398; cv=none; b=YV4Z7OrvFsxStfy+1pSoLBuc+HkP4rrld1cfdtHRTDdfjotaicQDc1x3FvkTiNlyAg49Kjix9tIk0axLicheM31YIp8u4sGPG1bC456GTOX2BHiAmPa1mhCfD0QZMy1yqthEY+tQPwxwFlR5YGLpxmksYrAcTucyj1eOGBj6AIw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724922398; c=relaxed/simple; bh=oo/dUElHFSvMNzt9dtUUMHlG68pacVcJeg0G/aF98eg=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=JwYBbCU1/EwUsmH3+YRyDMfw/JF9f6niFNhi7gyJMJ8KPmuSeLctgFUpXv7MqGUg2L8b8D6M0NDLMQGb4xUQV2hp6jDOOjzpOcjjOFcBrHWdH6ecvoBxQ3yXwMPsdm/NUSiQtcIvVOlzy6hZuqHerHpYw+3Fs/TNGXF4TKtD1w4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nCTVBWLB; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="nCTVBWLB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7357BC4CEC1; Thu, 29 Aug 2024 09:06:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724922398; bh=oo/dUElHFSvMNzt9dtUUMHlG68pacVcJeg0G/aF98eg=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=nCTVBWLB6FSV+hkOWtvobtE6l1VVwy7ybA6SWTi+SWZh6c7hErBKnCjrVEK4n7kCl BrIq4Ebu0ooLtmmm6w/kifjT0SUXN4UsZyH67f4RrRnLrbS8PcXUUOc7MixBGM3aXC eA3Vf5mGNADXIJ09wz44fhrVB8cy5mn3ryH+yV12pst4ktNy8dzZwAuMNU4ynuVG/J 7TnTRTGbaGVcbGOUUXo9lqTAZqVjaT+YynUujXxHfSU+Y+JLbbSk7WVGiUFShERPLt eWZSlKYUQycYsdLJjkcj1uKYlzO6psvLpXRP0+sG5HDdQFmLWKArg+vf3nfhxfvm6s 1pED8VyJiA7mw== Message-ID: Date: Thu, 29 Aug 2024 11:06:34 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] nfc: pn533: Add poll mod list filling check To: Paolo Abeni , Aleksandr Mishin , Samuel Ortiz Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, lvc-project@linuxtesting.org References: <20240827084822.18785-1-amishin@t-argos.ru> <26d3f7cf-1fd8-48b6-97be-ba6819a2ff85@redhat.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 29/08/2024 10:26, Paolo Abeni wrote: > > > On 8/27/24 10:48, Aleksandr Mishin wrote: >> In case of im_protocols value is 1 and tm_protocols value is 0 this >> combination successfully passes the check >> 'if (!im_protocols && !tm_protocols)' in the nfc_start_poll(). >> But then after pn533_poll_create_mod_list() call in pn533_start_poll() >> poll mod list will remain empty and dev->poll_mod_count will remain 0 >> which lead to division by zero. >> >> Normally no im protocol has value 1 in the mask, so this combination is >> not expected by driver. But these protocol values actually come from >> userspace via Netlink interface (NFC_CMD_START_POLL operation). So a >> broken or malicious program may pass a message containing a "bad" >> combination of protocol parameter values so that dev->poll_mod_count >> is not incremented inside pn533_poll_create_mod_list(), thus leading >> to division by zero. >> Call trace looks like: >> nfc_genl_start_poll() >> nfc_start_poll() >> ->start_poll() >> pn533_start_poll() >> >> Add poll mod list filling check. >> >> Found by Linux Verification Center (linuxtesting.org) with SVACE. >> >> Fixes: dfccd0f58044 ("NFC: pn533: Add some polling entropy") >> Signed-off-by: Aleksandr Mishin > > The issue looks real to me and the proposed fix the correct one, but > waiting a little more for Krzysztof feedback, as he expressed concerns > on v1. There was one month delay between my reply and clarifications from Fedor, so original patch is neither in my mailbox nor in my brain. Acked-by: Krzysztof Kozlowski However different problem is: shouldn't as well or instead nfc_genl_start_poll() validate the attributes received by netlink? We just pass them directly to the drivers and several other drivers might not expect random stuff there. Best regards, Krzysztof