{"id":2223198,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2223198/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260414171351.31212-1-fw@strlen.de/","project":{"id":26,"url":"http://patchwork.ozlabs.org/api/1.1/projects/26/?format=json","name":"Netfilter Development","link_name":"netfilter-devel","list_id":"netfilter-devel.vger.kernel.org","list_email":"netfilter-devel@vger.kernel.org","web_url":null,"scm_url":null,"webscm_url":null},"msgid":"<20260414171351.31212-1-fw@strlen.de>","date":"2026-04-14T17:13:46","name":"[nf,1/2] netfilter: conntrack: remove sprintf usage","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"1b60b283411e5b3996fa271520095dcc04b95598","submitter":{"id":1025,"url":"http://patchwork.ozlabs.org/api/1.1/people/1025/?format=json","name":"Florian Westphal","email":"fw@strlen.de"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260414171351.31212-1-fw@strlen.de/mbox/","series":[{"id":499877,"url":"http://patchwork.ozlabs.org/api/1.1/series/499877/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/list/?series=499877","date":"2026-04-14T17:13:46","name":"[nf,1/2] netfilter: conntrack: remove sprintf usage","version":1,"mbox":"http://patchwork.ozlabs.org/series/499877/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2223198/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2223198/checks/","tags":{},"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","netfilter-devel@vger.kernel.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.105.105.114; helo=tor.lore.kernel.org;\n envelope-from=netfilter-devel+bounces-11885-incoming=patchwork.ozlabs.org@vger.kernel.org;\n receiver=patchwork.ozlabs.org)","smtp.subspace.kernel.org;\n arc=none smtp.client-ip=91.216.245.30","smtp.subspace.kernel.org;\n dmarc=none (p=none dis=none) header.from=strlen.de","smtp.subspace.kernel.org;\n spf=pass smtp.mailfrom=Chamillionaire.breakpoint.cc"],"Received":["from tor.lore.kernel.org (tor.lore.kernel.org [172.105.105.114])\n\t(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)\n\t key-exchange x25519 server-signature ECDSA (secp384r1) server-digest SHA384)\n\t(No client certificate requested)\n\tby legolas.ozlabs.org (Postfix) with ESMTPS id 4fw9vS5zt2z1yCv\n\tfor ; Wed, 15 Apr 2026 03:17:40 +1000 (AEST)","from smtp.subspace.kernel.org (conduit.subspace.kernel.org\n [100.90.174.1])\n\tby tor.lore.kernel.org (Postfix) with ESMTP id E47703063A3A\n\tfor ; Tue, 14 Apr 2026 17:14:10 +0000 (UTC)","from localhost.localdomain 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c=relaxed/simple;\n\tbh=nZPP+VJqUM66G5XJx1eayQdRf3Esp9eX9+sQcwTMC90=;\n\th=From:To:Cc:Subject:Date:Message-ID:MIME-Version;\n b=oXRGmN+Ia8xxHLAjVeiO+eXE2CMsb/N0df++1Q7CFgPr8JPAb+2Zpp3KBbacLjgtg0ycGVzCVHTkzXy9k7dmwtyjuOs+mSSEq/fBIwLJlshAMaKvCgunyVena5Cnbynv8p1d2FWQw5engZgFjJK4Yj7qF+QO9LiH8oGsdf0NqtE=","ARC-Authentication-Results":"i=1; smtp.subspace.kernel.org;\n dmarc=none (p=none dis=none) header.from=strlen.de;\n spf=pass smtp.mailfrom=Chamillionaire.breakpoint.cc;\n arc=none smtp.client-ip=91.216.245.30","From":"Florian Westphal ","To":"","Cc":"Florian Westphal ,\n\tYiming Qian ","Subject":"[PATCH nf 1/2] netfilter: conntrack: remove sprintf usage","Date":"Tue, 14 Apr 2026 19:13:46 +0200","Message-ID":"<20260414171351.31212-1-fw@strlen.de>","X-Mailer":"git-send-email 2.52.0","Precedence":"bulk","X-Mailing-List":"netfilter-devel@vger.kernel.org","List-Id":"","List-Subscribe":"","List-Unsubscribe":"","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit"},"content":"Replace it with scnprintf, the buffer sizes are expected to be large enough\nto hold the result, no need for snprintf+overflow check.\n\nIncrease buffer size in mangle_content_len() while at it.\n\nBUG: KASAN: stack-out-of-bounds in vsnprintf+0xea5/0x1270\nWrite of size 1 at addr [..]\n vsnprintf+0xea5/0x1270\n sprintf+0xb1/0xe0\n mangle_content_len+0x1ac/0x280\n nf_nat_sdp_session+0x1cc/0x240\n process_sdp+0x8f8/0xb80\n process_invite_request+0x108/0x2b0\n process_sip_msg+0x5da/0xf50\n sip_help_tcp+0x45e/0x780\n nf_confirm+0x34d/0x990\n [..]\n\nFixes: 9fafcd7b2032 (\"[NETFILTER]: nf_conntrack/nf_nat: add SIP helper port\")\nReported-by: Yiming Qian \nSigned-off-by: Florian Westphal \n---\n net/netfilter/nf_nat_amanda.c | 2 +-\n net/netfilter/nf_nat_sip.c | 33 ++++++++++++++++++---------------\n 2 files changed, 19 insertions(+), 16 deletions(-)","diff":"diff --git a/net/netfilter/nf_nat_amanda.c b/net/netfilter/nf_nat_amanda.c\nindex 98deef6cde69..8f1054920a85 100644\n--- a/net/netfilter/nf_nat_amanda.c\n+++ b/net/netfilter/nf_nat_amanda.c\n@@ -50,7 +50,7 @@ static unsigned int help(struct sk_buff *skb,\n \t\treturn NF_DROP;\n \t}\n \n-\tsprintf(buffer, \"%u\", port);\n+\tsnprintf(buffer, sizeof(buffer), \"%u\", port);\n \tif (!nf_nat_mangle_udp_packet(skb, exp->master, ctinfo,\n \t\t\t\t protoff, matchoff, matchlen,\n \t\t\t\t buffer, strlen(buffer))) {\ndiff --git a/net/netfilter/nf_nat_sip.c b/net/netfilter/nf_nat_sip.c\nindex cf4aeb299bde..c845b6d1a2bd 100644\n--- a/net/netfilter/nf_nat_sip.c\n+++ b/net/netfilter/nf_nat_sip.c\n@@ -68,25 +68,27 @@ static unsigned int mangle_packet(struct sk_buff *skb, unsigned int protoff,\n }\n \n static int sip_sprintf_addr(const struct nf_conn *ct, char *buffer,\n+\t\t\t size_t size,\n \t\t\t const union nf_inet_addr *addr, bool delim)\n {\n \tif (nf_ct_l3num(ct) == NFPROTO_IPV4)\n-\t\treturn sprintf(buffer, \"%pI4\", &addr->ip);\n+\t\treturn scnprintf(buffer, size, \"%pI4\", &addr->ip);\n \telse {\n \t\tif (delim)\n-\t\t\treturn sprintf(buffer, \"[%pI6c]\", &addr->ip6);\n+\t\t\treturn scnprintf(buffer, size, \"[%pI6c]\", &addr->ip6);\n \t\telse\n-\t\t\treturn sprintf(buffer, \"%pI6c\", &addr->ip6);\n+\t\t\treturn scnprintf(buffer, size, \"%pI6c\", &addr->ip6);\n \t}\n }\n \n static int sip_sprintf_addr_port(const struct nf_conn *ct, char *buffer,\n+\t\t\t\t size_t size,\n \t\t\t\t const union nf_inet_addr *addr, u16 port)\n {\n \tif (nf_ct_l3num(ct) == NFPROTO_IPV4)\n-\t\treturn sprintf(buffer, \"%pI4:%u\", &addr->ip, port);\n+\t\treturn scnprintf(buffer, size, \"%pI4:%u\", &addr->ip, port);\n \telse\n-\t\treturn sprintf(buffer, \"[%pI6c]:%u\", &addr->ip6, port);\n+\t\treturn scnprintf(buffer, size, \"[%pI6c]:%u\", &addr->ip6, port);\n }\n \n static int map_addr(struct sk_buff *skb, unsigned int protoff,\n@@ -119,7 +121,7 @@ static int map_addr(struct sk_buff *skb, unsigned int protoff,\n \tif (nf_inet_addr_cmp(&newaddr, addr) && newport == port)\n \t\treturn 1;\n \n-\tbuflen = sip_sprintf_addr_port(ct, buffer, &newaddr, ntohs(newport));\n+\tbuflen = sip_sprintf_addr_port(ct, buffer, sizeof(buffer), &newaddr, ntohs(newport));\n \treturn mangle_packet(skb, protoff, dataoff, dptr, datalen,\n \t\t\t matchoff, matchlen, buffer, buflen);\n }\n@@ -212,7 +214,7 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,\n \t\t\t\t\t &addr, true) > 0 &&\n \t\t nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3) &&\n \t\t !nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.dst.u3)) {\n-\t\t\tbuflen = sip_sprintf_addr(ct, buffer,\n+\t\t\tbuflen = sip_sprintf_addr(ct, buffer, sizeof(buffer),\n \t\t\t\t\t&ct->tuplehash[!dir].tuple.dst.u3,\n \t\t\t\t\ttrue);\n \t\t\tif (!mangle_packet(skb, protoff, dataoff, dptr, datalen,\n@@ -229,7 +231,7 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,\n \t\t\t\t\t &addr, false) > 0 &&\n \t\t nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.dst.u3) &&\n \t\t !nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.src.u3)) {\n-\t\t\tbuflen = sip_sprintf_addr(ct, buffer,\n+\t\t\tbuflen = sip_sprintf_addr(ct, buffer, sizeof(buffer),\n \t\t\t\t\t&ct->tuplehash[!dir].tuple.src.u3,\n \t\t\t\t\tfalse);\n \t\t\tif (!mangle_packet(skb, protoff, dataoff, dptr, datalen,\n@@ -247,7 +249,7 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,\n \t\t htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port &&\n \t\t htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) {\n \t\t\t__be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port;\n-\t\t\tbuflen = sprintf(buffer, \"%u\", ntohs(p));\n+\t\t\tbuflen = scnprintf(buffer, sizeof(buffer), \"%u\", ntohs(p));\n \t\t\tif (!mangle_packet(skb, protoff, dataoff, dptr, datalen,\n \t\t\t\t\t poff, plen, buffer, buflen)) {\n \t\t\t\tnf_ct_helper_log(skb, ct, \"cannot mangle rport\");\n@@ -418,7 +420,8 @@ static unsigned int nf_nat_sip_expect(struct sk_buff *skb, unsigned int protoff,\n \n \tif (!nf_inet_addr_cmp(&exp->tuple.dst.u3, &exp->saved_addr) ||\n \t exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) {\n-\t\tbuflen = sip_sprintf_addr_port(ct, buffer, &newaddr, port);\n+\t\tbuflen = sip_sprintf_addr_port(ct, buffer, sizeof(buffer),\n+\t\t\t\t\t &newaddr, port);\n \t\tif (!mangle_packet(skb, protoff, dataoff, dptr, datalen,\n \t\t\t\t matchoff, matchlen, buffer, buflen)) {\n \t\t\tnf_ct_helper_log(skb, ct, \"cannot mangle packet\");\n@@ -438,8 +441,8 @@ static int mangle_content_len(struct sk_buff *skb, unsigned int protoff,\n {\n \tenum ip_conntrack_info ctinfo;\n \tstruct nf_conn *ct = nf_ct_get(skb, &ctinfo);\n+\tchar buffer[sizeof(\"4294967295\")];\n \tunsigned int matchoff, matchlen;\n-\tchar buffer[sizeof(\"65536\")];\n \tint buflen, c_len;\n \n \t/* Get actual SDP length */\n@@ -454,7 +457,7 @@ static int mangle_content_len(struct sk_buff *skb, unsigned int protoff,\n \t\t\t &matchoff, &matchlen) <= 0)\n \t\treturn 0;\n \n-\tbuflen = sprintf(buffer, \"%u\", c_len);\n+\tbuflen = scnprintf(buffer, sizeof(buffer), \"%u\", c_len);\n \treturn mangle_packet(skb, protoff, dataoff, dptr, datalen,\n \t\t\t matchoff, matchlen, buffer, buflen);\n }\n@@ -491,7 +494,7 @@ static unsigned int nf_nat_sdp_addr(struct sk_buff *skb, unsigned int protoff,\n \tchar buffer[INET6_ADDRSTRLEN];\n \tunsigned int buflen;\n \n-\tbuflen = sip_sprintf_addr(ct, buffer, addr, false);\n+\tbuflen = sip_sprintf_addr(ct, buffer, sizeof(buffer), addr, false);\n \tif (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen,\n \t\t\t sdpoff, type, term, buffer, buflen))\n \t\treturn 0;\n@@ -509,7 +512,7 @@ static unsigned int nf_nat_sdp_port(struct sk_buff *skb, unsigned int protoff,\n \tchar buffer[sizeof(\"nnnnn\")];\n \tunsigned int buflen;\n \n-\tbuflen = sprintf(buffer, \"%u\", port);\n+\tbuflen = scnprintf(buffer, sizeof(buffer), \"%u\", port);\n \tif (!mangle_packet(skb, protoff, dataoff, dptr, datalen,\n \t\t\t matchoff, matchlen, buffer, buflen))\n \t\treturn 0;\n@@ -529,7 +532,7 @@ static unsigned int nf_nat_sdp_session(struct sk_buff *skb, unsigned int protoff\n \tunsigned int buflen;\n \n \t/* Mangle session description owner and contact addresses */\n-\tbuflen = sip_sprintf_addr(ct, buffer, addr, false);\n+\tbuflen = sip_sprintf_addr(ct, buffer, sizeof(buffer), addr, false);\n \tif (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff,\n \t\t\t SDP_HDR_OWNER, SDP_HDR_MEDIA, buffer, buflen))\n \t\treturn 0;\n","prefixes":["nf","1/2"]}