In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
netfilter: nf_nat_sip: reload possible stale data pointer<\/p>\n
quoting sashiko:
\n ————————————————————————
\n [..] noticed a potential memory bug and header corruption involving the
\n SIP NAT helper.<\/p>\n
In net\/netfilter\/nf_nat_sip.c:nf_nat_sip():
\n\tif (skb_ensure_writable(skb, skb->len)) {
\n\t\tnf_ct_helper_log(skb, ct, “cannot mangle packet”);
\n\t\treturn NF_DROP;
\n\t}
\n\tuh = (void *)skb->data + protoff;
\n\tuh->dest = ct_sip_info->forced_dport;
\n\tif (!nf_nat_mangle_udp_packet(skb, ct, ctinfo, protoff,
\n\t\t\t\t 0, 0, NULL, 0)) {<\/p>\n
If a cloned or fragmented SKB is reallocated by skb_ensure_writable(), the
\n old data buffer is freed. However, nf_nat_sip() fails to update *dptr to
\n point to the new buffer.<\/p>\n
It also appears to use nf_nat_mangle_udp_packet() on what could be a TCP
\n packet, which would overwrite the sequence number with a checksum update.
\n ————————————————————————<\/p>\n
nf_conntrack_sip linerizes skbs, hence no fragmented skb can be seen.
\nBut clones are possible, so rebuild dptr.<\/p>\n
Disable nf_nat_mangle_udp_packet() branch for TCP streams.
\nIt doesn’t look like this can ever happen, else we should have received
\nbug reports about this, so just check the conntrack is UDP and drop
\notherwise.<\/p>\n
The calling conntrack_sip set ->forced_dport for SIP_HDR_VIA_UDP messages,
\nso I don’t think this is ever expected to be true for a TCP stream.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
netfilter: nf_nat_sip: reload possible stale data pointer<\/p>\n
quoting sashiko:
\n ——————————————————<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-6873","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/6873","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=6873"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=6873"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=6873"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}