calipso: keep BIG TCP payload_len in calipso_skbuff_setattr()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-99191
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-28 11:17:40 UTC
Updated2026-10-30 13:21:52 UTC
DescriptionIn 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.

Risk And Classification

EPSS: 0.001720000 probability, percentile 0.066420000 (date 2026-10-30)

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 81fbc812132cbc72a0f933b19bfd3a829bd946e4 e29d0a00c619ac794b05d64f4438204478137365 git Not specified
CNA Linux Linux affected 81fbc812132cbc72a0f933b19bfd3a829bd946e4 929dc8e2c9165bb651dca26b2c68067a3880406b git Not specified
CNA Linux Linux affected 81fbc812132cbc72a0f933b19bfd3a829bd946e4 1c9fcfca51e3c5cd46dd72a4da74d56eff183513 git Not specified
CNA Linux Linux affected 81fbc812132cbc72a0f933b19bfd3a829bd946e4 8ee0e03663826a76507048d58466b29321a57656 git Not specified
CNA Linux Linux affected 81fbc812132cbc72a0f933b19bfd3a829bd946e4 8070ed578b6b9134e045627fb745c887a806d46e git Not specified
CNA Linux Linux affected 5.19 Not specified
CNA Linux Linux unaffected 5.19 semver Not specified
CNA Linux Linux unaffected 6.6.161 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.115 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.59 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.13 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/929dc8e2c9165bb651dca26b2c68067a3880406b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/1c9fcfca51e3c5cd46dd72a4da74d56eff183513 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e29d0a00c619ac794b05d64f4438204478137365 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8ee0e03663826a76507048d58466b29321a57656 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8070ed578b6b9134e045627fb745c887a806d46e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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