ipv6: sr: enforce exact attribute length for SEG6_ATTR_DST

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98531
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-18 16:17:04 UTC
Updated2026-10-18 16:17:04 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ipv6: sr: enforce exact attribute length for SEG6_ATTR_DST In seg6_genl_policy, SEG6_ATTR_DST is defined with .type = NLA_BINARY and .len = sizeof(struct in6_addr). For NLA_BINARY, .len only enforces the maximum payload length and permits shorter payloads (e.g., 0 bytes). When seg6_genl_set_tunsrc() copies sizeof(struct in6_addr) bytes via kmemdup(val, sizeof(*val), GFP_KERNEL), a short SEG6_ATTR_DST attribute triggers a 16-byte out-of-bounds read past skb->tail into uninitialized skb->head memory, which is stored in sdata->tun_src and leaked back to userspace via SEG6_CMD_GET_TUNSRC. Switch SEG6_ATTR_DST in seg6_genl_policy to NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)) so that generic netlink validation rejects any attribute whose length is not exactly sizeof(struct in6_addr) with -ERANGE. Tested in QEMU against Linux 7.3.0-rc3 by sending a SEG6_CMD_SET_TUNSRC Generic Netlink message with a 0-byte SEG6_ATTR_DST attribute followed by SEG6_CMD_GET_TUNSRC. On the unfixed kernel, SEG6_CMD_SET_TUNSRC succeeds (err = 0) and SEG6_CMD_GET_TUNSRC leaks 16 bytes of uninitialized kernel heap memory (tun_src = 836a61ecc4d25a1042a8d60411cfb378); with this patch applied, SEG6_CMD_SET_TUNSRC is rejected by netlink policy validation with -ERANGE (-34) and tun_src remains zeroed.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 915d7e5e5930b4f01d0971d93b9b25ed17d221aa 050a0aa3c80907b8c60a396b7e04d48d8b1a9e70 git Not specified
CNA Linux Linux affected 915d7e5e5930b4f01d0971d93b9b25ed17d221aa 209eefebee54c4a5f01d68b61e8ac9881eca2de9 git Not specified
CNA Linux Linux affected 915d7e5e5930b4f01d0971d93b9b25ed17d221aa e3ac68c1cdc2535d127b2bfd50c263d16c8e4199 git Not specified
CNA Linux Linux affected 915d7e5e5930b4f01d0971d93b9b25ed17d221aa 66bf65fa109326e4c4ddeb0b94093379f72838fd git Not specified
CNA Linux Linux affected 915d7e5e5930b4f01d0971d93b9b25ed17d221aa 195813bb7324c338eaba0aaa02b18681ee65b670 git Not specified
CNA Linux Linux affected 915d7e5e5930b4f01d0971d93b9b25ed17d221aa 6fcfc362344edea745a69f3a705de50b731f3418 git Not specified
CNA Linux Linux affected 915d7e5e5930b4f01d0971d93b9b25ed17d221aa 94214cf0a08dd2c5f37aeeea46078d9dfe8e4a0e git Not specified
CNA Linux Linux affected 915d7e5e5930b4f01d0971d93b9b25ed17d221aa 2d959c75c27f90e9ec489d18ce5ee6b852ad4741 git Not specified
CNA Linux Linux affected 4.10 Not specified
CNA Linux Linux unaffected 4.10 semver Not specified
CNA Linux Linux unaffected 5.10.271 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.222 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.189 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.158 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.112 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.55 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.9 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/195813bb7324c338eaba0aaa02b18681ee65b670 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e3ac68c1cdc2535d127b2bfd50c263d16c8e4199 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/050a0aa3c80907b8c60a396b7e04d48d8b1a9e70 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/94214cf0a08dd2c5f37aeeea46078d9dfe8e4a0e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6fcfc362344edea745a69f3a705de50b731f3418 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/209eefebee54c4a5f01d68b61e8ac9881eca2de9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/66bf65fa109326e4c4ddeb0b94093379f72838fd 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2d959c75c27f90e9ec489d18ce5ee6b852ad4741 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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