From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.237 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793410104; b=V1j87sNHanTpuoolLfDe9k19RtucfLe684I+0ngRrBr2z08As+ok3hpTfjfnZcfudzq4 v4R8yLm2p9zj+whrZ2QBlsx58qWmrMnhpM1UfWOEsNGABlWdkTWCx/VRy1dv2klsnpBeA Mk1BLGEw8DclEGYhopsLRaiZMTKCqC23r3hTGmY/w7C3fZcMITK1WGJHd1voIAz0R3wzU KoqTSD5kR4DDpwyo8f4SnBavMFhxwQ6LdB5fHDg5XVeXFbEVclDt2KR+lcosioqPTtvsi HDPtmu/8LdaVfoK1g4MNtm3Uro1NI0neQL/n7ZxfppUp2H5uk34SLW+Boec7NNXO61g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793410104; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:Content-Language:From:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=a6ooV5rVY1GQuE6ouKZNNisI0guDE/GpOjIpdYXk4Rs=; b=OGZRL7xtwF5SwZI5TcoUwlCbcw4A/igp5VqyVu6GByoPh9yaJqBQWdHUzxV/nF5uRkgW wCQUfqxHjcrixB6L+pnL6QTjCkTBrVRqpfUvH0aiIWIz9jC8Vs/prQhYEmL1LtOt2zG9C o6vsAsbz1Qqh87jb7pSXE2QbzTPEMy9LpzQ+3MHePOw8cWnPmZEEAEStS3OVy15eg227o D7SMdURGPg3vXcZn56JlN3Sa4wipPKRhgXmX1TmfCknIwAfdjrOTznFYy1rfunpCRpIbn hwZ/MYIeuXnsNU5Q74fLKDuJbeJd/fPBJds6Tyc6Sy9hMXxYTkatLr7aj/ppX6y3S6Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=Pq9hKRpu; arc=none smtp.remote-ip=95.215.58.237 Received: from mta1.migadu.com (out-237.mta1.migadu.com [95.215.58.237]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 57E25606A31D for ; Sat, 31 Oct 2026 01:28:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 57E25606A31D Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=Pq9hKRpu X-Envelope-To: linux-ppp@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=3UXlybLI0iJDYqrDEMOmBWP5abFQsCQpxQAYz2OkJnc=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1793410100; v=1; x=1794014900; b=Pq9hKRpuxr+cse55KGlwBn9UFzX5RIiJ1S35PW1gNCjs0PtQj8h6TeVzFoalPYOH9HIbQEbp L2iK2eodgtisxDXfBuuqNCl2dJbsPMaZGJDw3H9zHuZminoWJ4nt2nch5lnWSmU7gGgGQPLNHKl 9agD44Txr2eIAuuH5lPUvoDQ= X-Envelope-To: linux-ppp@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 1701bc76d040e0a1; Sat, 31 Oct 2026 01:28:19 +0000 X-Mizu-Trace-ID: 1701bc76d040e0a1 X-Migadu-Flow: FLOW_OUT Message-ID: <84396bab-166b-435f-9663-0aa2939de3fc@linux.dev> Date: Sat, 31 Oct 2026 09:28:10 +0800 X-Mailing-List: linux-ppp@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net] ppp: remove SC_MUST_COMP To: netdev-bot+sashiko@kernel.org Cc: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, leitao@debian.org, norbert@doyensec.com, hataegu0826@gmail.com, paulus@ozlabs.org, Brice.Goglin@ens-lyon.org, akpm@osdl.org, Matt_Domsch@dell.com, linux-ppp@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20261029074935.40509-1-qingfang.deng@linux.dev> <179339596607.3131.10030375792154782283@kernel.org> Content-Language: en-US From: Qingfang Deng In-Reply-To: <179339596607.3131.10030375792154782283@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 10/31/2026 5:32 AM, netdev-bot+sashiko@kernel.org wrote: > [Severity: Medium] > Does the fix need the define to be removed from the UAPI header? > > PPPIOCSFLAGS already masks the user value with the kernel-internal > SC_FLAG_BITS: > > drivers/net/ppp/ppp_generic.c:ppp_ioctl() { > ... > ppp->flags = val & SC_FLAG_BITS; > ... > } > > Removing the bit from SC_FLAG_BITS (and SC_MASK), together with the two > checks, looks like enough to stop SC_DC_ERROR from being stored as a > config flag. > > Deleting the define is a separate change at the source level. Userspace > that includes , directly or through , > and refers to SC_MUST_COMP would no longer build. > > The commit message calls the flag unused, but the evidence is that one > pppd integration from 2005 never landed upstream. That does not rule out > out-of-tree pppd MPPE forks or other daemons that use the name. > > With the Fixes: tag pointing at a 2005 commit, this header change will > likely be backported to the stable kernel-headers as well. > > Would it work to keep the define, with a comment that the kernel ignores > it and that it aliases SC_DC_ERROR, while still dropping it from > SC_FLAG_BITS and SC_MASK and removing the checks? I found no trace of existing users (searched GitHub). Even _if_ there are any, _and_ SC_MUST_COMP does not alias SC_DC_ERROR, the logic is still flawed - received packets are silently dropped without noticing the userspace. If the goal is to prevent the removal from backports, I may split out the removal part into a net-next patch.