From: Florian Westphal Date: Tue, 14 Apr 2026 17:13:46 +0000 (+0200) Subject: netfilter: conntrack: remove sprintf usage X-Git-Tag: v7.1-rc1~36^2~23^2~5 X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=6e7066bdb481a87fe88c4fa563e348c03b2d373d;p=thirdparty%2Fkernel%2Flinux.git netfilter: conntrack: remove sprintf usage Replace it with scnprintf, the buffer sizes are expected to be large enough to hold the result, no need for snprintf+overflow check. Increase buffer size in mangle_content_len() while at it. BUG: KASAN: stack-out-of-bounds in vsnprintf+0xea5/0x1270 Write of size 1 at addr [..] vsnprintf+0xea5/0x1270 sprintf+0xb1/0xe0 mangle_content_len+0x1ac/0x280 nf_nat_sdp_session+0x1cc/0x240 process_sdp+0x8f8/0xb80 process_invite_request+0x108/0x2b0 process_sip_msg+0x5da/0xf50 sip_help_tcp+0x45e/0x780 nf_confirm+0x34d/0x990 [..] Fixes: 9fafcd7b2032 ("[NETFILTER]: nf_conntrack/nf_nat: add SIP helper port") Reported-by: Yiming Qian Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- diff --git a/net/netfilter/nf_nat_amanda.c b/net/netfilter/nf_nat_amanda.c index 98deef6cde69..8f1054920a85 100644 --- a/net/netfilter/nf_nat_amanda.c +++ b/net/netfilter/nf_nat_amanda.c @@ -50,7 +50,7 @@ static unsigned int help(struct sk_buff *skb, return NF_DROP; } - sprintf(buffer, "%u", port); + snprintf(buffer, sizeof(buffer), "%u", port); if (!nf_nat_mangle_udp_packet(skb, exp->master, ctinfo, protoff, matchoff, matchlen, buffer, strlen(buffer))) { diff --git a/net/netfilter/nf_nat_sip.c b/net/netfilter/nf_nat_sip.c index cf4aeb299bde..c845b6d1a2bd 100644 --- a/net/netfilter/nf_nat_sip.c +++ b/net/netfilter/nf_nat_sip.c @@ -68,25 +68,27 @@ static unsigned int mangle_packet(struct sk_buff *skb, unsigned int protoff, } static int sip_sprintf_addr(const struct nf_conn *ct, char *buffer, + size_t size, const union nf_inet_addr *addr, bool delim) { if (nf_ct_l3num(ct) == NFPROTO_IPV4) - return sprintf(buffer, "%pI4", &addr->ip); + return scnprintf(buffer, size, "%pI4", &addr->ip); else { if (delim) - return sprintf(buffer, "[%pI6c]", &addr->ip6); + return scnprintf(buffer, size, "[%pI6c]", &addr->ip6); else - return sprintf(buffer, "%pI6c", &addr->ip6); + return scnprintf(buffer, size, "%pI6c", &addr->ip6); } } static int sip_sprintf_addr_port(const struct nf_conn *ct, char *buffer, + size_t size, const union nf_inet_addr *addr, u16 port) { if (nf_ct_l3num(ct) == NFPROTO_IPV4) - return sprintf(buffer, "%pI4:%u", &addr->ip, port); + return scnprintf(buffer, size, "%pI4:%u", &addr->ip, port); else - return sprintf(buffer, "[%pI6c]:%u", &addr->ip6, port); + return scnprintf(buffer, size, "[%pI6c]:%u", &addr->ip6, port); } static int map_addr(struct sk_buff *skb, unsigned int protoff, @@ -119,7 +121,7 @@ static int map_addr(struct sk_buff *skb, unsigned int protoff, if (nf_inet_addr_cmp(&newaddr, addr) && newport == port) return 1; - buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, ntohs(newport)); + buflen = sip_sprintf_addr_port(ct, buffer, sizeof(buffer), &newaddr, ntohs(newport)); return mangle_packet(skb, protoff, dataoff, dptr, datalen, matchoff, matchlen, buffer, buflen); } @@ -212,7 +214,7 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff, &addr, true) > 0 && nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3) && !nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.dst.u3)) { - buflen = sip_sprintf_addr(ct, buffer, + buflen = sip_sprintf_addr(ct, buffer, sizeof(buffer), &ct->tuplehash[!dir].tuple.dst.u3, true); if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, @@ -229,7 +231,7 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff, &addr, false) > 0 && nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.dst.u3) && !nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.src.u3)) { - buflen = sip_sprintf_addr(ct, buffer, + buflen = sip_sprintf_addr(ct, buffer, sizeof(buffer), &ct->tuplehash[!dir].tuple.src.u3, false); if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, @@ -247,7 +249,7 @@ static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff, htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port && htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) { __be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port; - buflen = sprintf(buffer, "%u", ntohs(p)); + buflen = scnprintf(buffer, sizeof(buffer), "%u", ntohs(p)); if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, poff, plen, buffer, buflen)) { nf_ct_helper_log(skb, ct, "cannot mangle rport"); @@ -418,7 +420,8 @@ static unsigned int nf_nat_sip_expect(struct sk_buff *skb, unsigned int protoff, if (!nf_inet_addr_cmp(&exp->tuple.dst.u3, &exp->saved_addr) || exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) { - buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, port); + buflen = sip_sprintf_addr_port(ct, buffer, sizeof(buffer), + &newaddr, port); if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, matchoff, matchlen, buffer, buflen)) { nf_ct_helper_log(skb, ct, "cannot mangle packet"); @@ -438,8 +441,8 @@ static int mangle_content_len(struct sk_buff *skb, unsigned int protoff, { enum ip_conntrack_info ctinfo; struct nf_conn *ct = nf_ct_get(skb, &ctinfo); + char buffer[sizeof("4294967295")]; unsigned int matchoff, matchlen; - char buffer[sizeof("65536")]; int buflen, c_len; /* Get actual SDP length */ @@ -454,7 +457,7 @@ static int mangle_content_len(struct sk_buff *skb, unsigned int protoff, &matchoff, &matchlen) <= 0) return 0; - buflen = sprintf(buffer, "%u", c_len); + buflen = scnprintf(buffer, sizeof(buffer), "%u", c_len); return mangle_packet(skb, protoff, dataoff, dptr, datalen, matchoff, matchlen, buffer, buflen); } @@ -491,7 +494,7 @@ static unsigned int nf_nat_sdp_addr(struct sk_buff *skb, unsigned int protoff, char buffer[INET6_ADDRSTRLEN]; unsigned int buflen; - buflen = sip_sprintf_addr(ct, buffer, addr, false); + buflen = sip_sprintf_addr(ct, buffer, sizeof(buffer), addr, false); if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff, type, term, buffer, buflen)) return 0; @@ -509,7 +512,7 @@ static unsigned int nf_nat_sdp_port(struct sk_buff *skb, unsigned int protoff, char buffer[sizeof("nnnnn")]; unsigned int buflen; - buflen = sprintf(buffer, "%u", port); + buflen = scnprintf(buffer, sizeof(buffer), "%u", port); if (!mangle_packet(skb, protoff, dataoff, dptr, datalen, matchoff, matchlen, buffer, buflen)) return 0; @@ -529,7 +532,7 @@ static unsigned int nf_nat_sdp_session(struct sk_buff *skb, unsigned int protoff unsigned int buflen; /* Mangle session description owner and contact addresses */ - buflen = sip_sprintf_addr(ct, buffer, addr, false); + buflen = sip_sprintf_addr(ct, buffer, sizeof(buffer), addr, false); if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff, SDP_HDR_OWNER, SDP_HDR_MEDIA, buffer, buflen)) return 0;