From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.netfilter.org (mail.netfilter.org [217.70.190.124]) (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 3442933CEBB; Thu, 26 Mar 2026 20:21:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.190.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774556511; cv=none; b=JQvnH9elcWxC3m72j2O4aglkFoNVhl4VpzHKzBf2CxlUvV9k/g+B9cDfCW4KWUjheHPxjFn64IR6leQBzd9GsPVrdHIGB7Ls3Pd5FNRxne1EyNjv50cIeKUqjs70N4ChlQY47V/qWJZiRdH+eBL6VFRZOqAXNo6HVKpJ9QbwTMQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774556511; c=relaxed/simple; bh=sjBIaQIJ3lM8oaURKVY3teKRZko/3BU/LQ5VCIK1n1w=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Povc/nRdcJHnkbjt3Fb/OROP07VkUNY72j/361lyp7JU+LG4CFcWMUdCYfqvxpBa1LUVROH9BvTr+GPb6035XOxN+MWBXCakJ4h7kXjBGuKyr6iPHyda4vclGf57dxk45oBhAYzLFpPywlbukbiMSIUNSXF0RBMPwTmgYslBuBI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org; spf=pass smtp.mailfrom=netfilter.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b=PfpHeDGn; arc=none smtp.client-ip=217.70.190.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=netfilter.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=netfilter.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org header.b="PfpHeDGn" Received: from netfilter.org (mail-agni [217.70.190.124]) by mail.netfilter.org (Postfix) with UTF8SMTPSA id DDAA160262; Thu, 26 Mar 2026 21:21:46 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org; s=2025; t=1774556507; bh=XVG1PdwNY/KMdNBwdSih/WCTXGUheIF/+ZYN0DkQ1Aw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=PfpHeDGnDQjZouFiuDFWOTp+Z7MqLYSmhGwJkqh7OrIlVxfe19VpQxFIiKK3UAvrz qfVnvnpVt1zSd41E9+6+T0RGjPdMatvAohvEwKg2L0PpX0pixN2cTmHL+eR+a/32yx B8U+5MtHLbBAAJD96czYLgeYVJ1a8okuwDiFGEVSN/bv9iFf7qAaSuxFsEbEm65LLu tLMwsVc3iuSMzLqt+AcUz6Scm7/zkmEbGJPGoJjWK0ZGGDOAb1780Fr7r0A9IUm98a tHKo+XKRA/8zpOBfwkifrQR3rFrq8tLEgIdv3y0KiahjsTyTvev+Rdon9tr8C0aW+L zrbEK60vbejIQ== Date: Thu, 26 Mar 2026 21:21:43 +0100 From: Pablo Neira Ayuso To: Weiming Shi Cc: Florian Westphal , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Phil Sutter , Simon Horman , netfilter-devel@vger.kernel.org, coreteam@netfilter.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Xiang Mei Subject: Re: [PATCH nf] netfilter: nf_conntrack_sip: fix use of uninitialized rtp_addr in process_sdp Message-ID: References: <20260323080727.2932866-3-bestswngs@gmail.com> 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: <20260323080727.2932866-3-bestswngs@gmail.com> On Mon, Mar 23, 2026 at 04:07:29PM +0800, Weiming Shi wrote: > process_sdp() declares union nf_inet_addr rtp_addr on the stack and > passes it to the nf_nat_sip sdp_session hook after walking the SDP > media descriptions. However rtp_addr is only initialized inside the > media loop when a recognized media type with a non-zero port is found. > > If the SDP body contains no m= lines, only inactive media sections > (m=audio 0 ...) or only unrecognized media types, rtp_addr is never > assigned. Despite that, the function still calls hooks->sdp_session() > with &rtp_addr, causing nf_nat_sdp_session() to format the stale stack > value as an IP address and rewrite the SDP session owner and connection > lines with it. > > With CONFIG_INIT_STACK_ALL_ZERO (default on most distributions) this > results in the session-level o= and c= addresses being rewritten to > 0.0.0.0 for inactive SDP sessions. Without stack auto-init the > rewritten address is whatever happened to be on the stack. > > Fix this by pre-initializing rtp_addr from the session-level connection > address (caddr) when available, and tracking via a have_rtp_addr flag > whether any valid address was established. Skip the sdp_session hook > entirely when no valid address exists. > > Fixes: 4ab9e64e5e3c ("[NETFILTER]: nf_nat_sip: split up SDP mangling") > Reported-by: Xiang Mei > Signed-off-by: Weiming Shi > --- > net/netfilter/nf_conntrack_sip.c | 14 ++++++++++---- > 1 file changed, 10 insertions(+), 4 deletions(-) > > diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c > index 4ab5ef71d96db..17af0ff4ea7ab 100644 > --- a/net/netfilter/nf_conntrack_sip.c > +++ b/net/netfilter/nf_conntrack_sip.c > @@ -1040,6 +1040,7 @@ static int process_sdp(struct sk_buff *skb, unsigned int protoff, > unsigned int port; > const struct sdp_media_type *t; > int ret = NF_ACCEPT; > + bool have_rtp_addr = false; > > hooks = rcu_dereference(nf_nat_sip_hooks); > > @@ -1056,8 +1057,11 @@ static int process_sdp(struct sk_buff *skb, unsigned int protoff, > caddr_len = 0; > if (ct_sip_parse_sdp_addr(ct, *dptr, sdpoff, *datalen, > SDP_HDR_CONNECTION, SDP_HDR_MEDIA, > - &matchoff, &matchlen, &caddr) > 0) > + &matchoff, &matchlen, &caddr) > 0) { > caddr_len = matchlen; > + memcpy(&rtp_addr, &caddr, sizeof(rtp_addr)); > + have_rtp_addr = true; > + } > > mediaoff = sdpoff; > for (i = 0; i < ARRAY_SIZE(sdp_media_types); ) { > @@ -1091,9 +1095,11 @@ static int process_sdp(struct sk_buff *skb, unsigned int protoff, > &matchoff, &matchlen, &maddr) > 0) { > maddr_len = matchlen; > memcpy(&rtp_addr, &maddr, sizeof(rtp_addr)); > - } else if (caddr_len) > + have_rtp_addr = true; > + } else if (caddr_len) { > memcpy(&rtp_addr, &caddr, sizeof(rtp_addr)); > - else { > + have_rtp_addr = true; After this update, this loop sets over rtp_addr, but this was already set by ct_sip_parse_sdp_addr() a bit above. This new chunk results in: } else if (caddr_len) { memcpy(&rtp_addr, &caddr, sizeof(rtp_addr)); have_rtp_addr = true; which is not needed? Why does caddr need to be copied over and over again to rtp_addr? > + } else { > nf_ct_helper_log(skb, ct, "cannot parse SDP message"); > return NF_DROP; > }