{"id":2225370,"url":"http://patchwork.ozlabs.org/api/1.1/patches/2225370/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260420220215.111510-4-pablo@netfilter.org/","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":"<20260420220215.111510-4-pablo@netfilter.org>","date":"2026-04-20T22:02:10","name":"[net,3/8] netfilter: conntrack: remove sprintf usage","commit_ref":null,"pull_url":null,"state":"accepted","archived":true,"hash":"1b60b283411e5b3996fa271520095dcc04b95598","submitter":{"id":1315,"url":"http://patchwork.ozlabs.org/api/1.1/people/1315/?format=json","name":"Pablo Neira Ayuso","email":"pablo@netfilter.org"},"delegate":{"id":11902,"url":"http://patchwork.ozlabs.org/api/1.1/users/11902/?format=json","username":"strlen","first_name":"Florian","last_name":"Westphal","email":"fw@strlen.de"},"mbox":"http://patchwork.ozlabs.org/project/netfilter-devel/patch/20260420220215.111510-4-pablo@netfilter.org/mbox/","series":[{"id":500691,"url":"http://patchwork.ozlabs.org/api/1.1/series/500691/?format=json","web_url":"http://patchwork.ozlabs.org/project/netfilter-devel/list/?series=500691","date":"2026-04-20T22:02:07","name":"[net,1/8] netfilter: nft_osf: restrict it to ipv4","version":1,"mbox":"http://patchwork.ozlabs.org/series/500691/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2225370/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2225370/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\tdkim=pass (2048-bit key;\n unprotected) header.d=netfilter.org header.i=@netfilter.org\n header.a=rsa-sha256 header.s=2025 header.b=ToVhpBxZ;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=172.232.135.74; helo=sto.lore.kernel.org;\n envelope-from=netfilter-devel+bounces-12097-incoming=patchwork.ozlabs.org@vger.kernel.org;\n receiver=patchwork.ozlabs.org)","smtp.subspace.kernel.org;\n\tdkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org\n header.b=\"ToVhpBxZ\"","smtp.subspace.kernel.org;\n arc=none smtp.client-ip=217.70.190.124","smtp.subspace.kernel.org;\n dmarc=none (p=none dis=none) header.from=netfilter.org","smtp.subspace.kernel.org;\n spf=pass smtp.mailfrom=netfilter.org"],"Received":["from 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spf=pass smtp.mailfrom=netfilter.org;\n dkim=pass (2048-bit key) header.d=netfilter.org header.i=@netfilter.org\n header.b=ToVhpBxZ; arc=none smtp.client-ip=217.70.190.124","DKIM-Signature":"v=1; a=rsa-sha256; c=relaxed/relaxed; d=netfilter.org;\n\ts=2025; t=1776722543;\n\tbh=QfjrvEMigLmW4gaPRVPEIkGuoJt1xZ0L/ydTlhts/NQ=;\n\th=From:To:Cc:Subject:Date:In-Reply-To:References:From;\n\tb=ToVhpBxZl83mv5IBIShC6DK71eGo+xECsY3sY/9SBGDdVl7WHOJl8MqPyIEnoKcTs\n\t wICZC/JRviANuLYHx4tsm5MjcElYm8WWumVQNU0UcWog/fXcOeulyDNL/tw/IrGOlm\n\t S+tuHKGPI5ZnGV2qNilqISvfXPqa6VTsJ6xuE/zdwuiJB9knR00FZbSxTe3nO1E8m6\n\t jXxMg2qK+G2hre1FLEMT69D6wVRwIeHVgWCQb+QK/OIbrLNiwNcQpjq3fvraFj8fDZ\n\t Fv45vEssqHvxM7kU2KN9H7xfY0WRBUqC16vceGXKuYrfuYfG9jBUR22SFd1LeiVFgo\n\t qFPqpAdGTNMoA==","From":"Pablo Neira Ayuso ","To":"netfilter-devel@vger.kernel.org","Cc":"davem@davemloft.net,\n\tnetdev@vger.kernel.org,\n\tkuba@kernel.org,\n\tpabeni@redhat.com,\n\tedumazet@google.com,\n\tfw@strlen.de,\n\thorms@kernel.org","Subject":"[PATCH net 3/8] netfilter: conntrack: remove sprintf usage","Date":"Tue, 21 Apr 2026 00:02:10 +0200","Message-ID":"<20260420220215.111510-4-pablo@netfilter.org>","X-Mailer":"git-send-email 2.47.3","In-Reply-To":"<20260420220215.111510-1-pablo@netfilter.org>","References":"<20260420220215.111510-1-pablo@netfilter.org>","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":"From: Florian Westphal \n\nReplace 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 \nSigned-off-by: Pablo Neira Ayuso \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":["net","3/8"]}