Wind River Support Network

Description

In the Linux kernel, the following vulnerability has been resolved:  calipso: keep BIG TCP payload_len in calipso_skbuff_setattr()  calipso_skbuff_setattr() adjusts payload_len by the length of the option it inserts or resizes:  	payload = ntohs(ip6_hdr->payload_len); 	ip6_hdr->payload_len = htons(payload + len_delta);  GRO can build BIG TCP packets larger than IPV6_MAXPLEN, and stores payload_len == 0 for them; ipv6_payload_len() then falls back to skb->len.  For such a packet forwarded to a destination mapped to CALIPSO, the code above writes len_delta (or 65536 + len_delta when shrinking) into payload_len, and ipv6_payload_len() no longer falls back to skb->len.  nf_tables, conntrack and sch_cake rely on it.  The same arithmetic also wraps when a packet grows past IPV6_MAXPLEN, and a BIG TCP packet that shrinks below IPV6_MAXPLEN should get its real length back.  Set payload_len from the skb length with ipv6_set_payload_len(), which stores 0 above IPV6_MAXPLEN and the real length otherwise, as ipv6_gro_complete() does.  The network header was just reset to skb->data, so skb->len - sizeof(*ip6_hdr) is the payload length.  Tested on one kernel (arm64, QEMU) with SELinux permissive, a minimal mdp-generated policy (network_peer_controls=1), "netlabelctl calipso add pass doi:16" and a NetLabel mapping of fd00:2::/64 to CALIPSO DOI 16.  calipso_skbuff_setattr() was called through netlbl_skbuff_setattr() from a test-only debugfs hook (not part of this patch) adding a level-only label; payload_len after the call:    case                         before fix   after fix   real length   1000, unlabeled                    1016        1016          1016   70000 GSO, payload_len 0             16           0         70016   65530 GSO, grows past MAXPLEN        10           0         65546   65540 GSO with a 24 byte hop   header, shrinks below MAXPLEN     65528       65532         65532   1000 with a 24 byte hop header      992         992           992  (0 means ipv6_payload_len() returns the real length.)  On the forward path, with a client injecting unlabeled UDP through a router to a server, the router adds the CALIPSO option and the server delivers all datagrams (Udp6InDatagrams 5, Ip6InTruncatedPkts 0) with this patch.
Data source: kernel.org (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

CVEs

• CVE-2026-99191