From: Lukas Johannes Möller Date: Tue, 10 Mar 2026 21:49:01 +0000 (+0000) Subject: netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp() X-Git-Tag: v7.0-rc5~31^2~31^2~8 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fbce58e719a17aa215c724473fd5baaa4a8dc57c;p=thirdparty%2Flinux.git netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp() sip_help_tcp() parses the SIP Content-Length header with simple_strtoul(), which returns unsigned long, but stores the result in unsigned int clen. On 64-bit systems, values exceeding UINT_MAX are silently truncated before computing the SIP message boundary. For example, Content-Length 4294967328 (2^32 + 32) is truncated to 32, causing the parser to miscalculate where the current message ends. The loop then treats trailing data in the TCP segment as a second SIP message and processes it through the SDP parser. Fix this by changing clen to unsigned long to match the return type of simple_strtoul(), and reject Content-Length values that exceed the remaining TCP payload length. Fixes: f5b321bd37fb ("netfilter: nf_conntrack_sip: add TCP support") Signed-off-by: Lukas Johannes Möller Signed-off-by: Florian Westphal --- diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c index ca748f8dbff1..4ab5ef71d96d 100644 --- a/net/netfilter/nf_conntrack_sip.c +++ b/net/netfilter/nf_conntrack_sip.c @@ -1534,11 +1534,12 @@ static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff, { struct tcphdr *th, _tcph; unsigned int dataoff, datalen; - unsigned int matchoff, matchlen, clen; + unsigned int matchoff, matchlen; unsigned int msglen, origlen; const char *dptr, *end; s16 diff, tdiff = 0; int ret = NF_ACCEPT; + unsigned long clen; bool term; if (ctinfo != IP_CT_ESTABLISHED && @@ -1573,6 +1574,9 @@ static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff, if (dptr + matchoff == end) break; + if (clen > datalen) + break; + term = false; for (; end + strlen("\r\n\r\n") <= dptr + datalen; end++) { if (end[0] == '\r' && end[1] == '\n' &&