net: ipv6: keep room for the mac header in dst_dev_overhead()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-98570
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-10-18 16:17:09 UTC
Updated2026-10-19 10:19:15 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net: ipv6: keep room for the mac header in dst_dev_overhead() The seg6, ioam6 and rpl lwtunnels size their skb_cow_head() request as the length they are about to push plus dst_dev_overhead(), then push the new headers and rebuild the mac header below them with skb_mac_header_rebuild(). That rebuild needs skb->mac_len of headroom, but dst_dev_overhead() leaves LL_RESERVED_SPACE() of the egress device, 16 bytes for plain Ethernet. Where the mac header is longer than that, as it is on ingress through a VLAN device with reorder_hdr off, the rebuild runs out of room: skb_set_mac_header(skb, -skb->mac_len) computes a negative offset, stores it unchecked in the u16 skb->mac_header, and the memmove that follows writes skb->mac_len bytes about 64 KB past skb->head. Forwarding plain ping6 traffic through such a device reproduces it on all five seg6 encapsulation modes and on the rpl and ioam6 inline paths; skb->mac_header comes back as 65534 on a 704-byte head. Return the larger of the two. The helper already returns skb->mac_len when it has no dst, so this only makes the other branch agree, and it covers every caller rather than each call site in turn.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected dce525185bc92864e5a318040285ee070563fe34 36c07127924f11fc5741a780abcaaf808fe9ef13 git Not specified
CNA Linux Linux affected dce525185bc92864e5a318040285ee070563fe34 87cd6b717e4069dca34e0866e57eaeb44d3b173e git Not specified
CNA Linux Linux affected 8471e228448a818e4c27cab4b681b2e758e46cf5 git Not specified
CNA Linux Linux affected c432cd18a07b623651ed15ea167bd303467004cc git Not specified
CNA Linux Linux affected 634710a372ba65bee667c2f6e58a97658c639eab git Not specified
CNA Linux Linux affected c447c5a9c47bb4858ab12bf90879fe595d2b7f46 git Not specified
CNA Linux Linux affected ab9de9c48316d2622d3bf353916b99971570e2c9 git Not specified
CNA Linux Linux affected 2fcc9f3798ef82399564d247458e69abd10e683b git Not specified
CNA Linux Linux affected 371d8dc298b4f59e99b4564ac5d906fce0932c69 git Not specified
CNA Linux Linux affected b26f015dfb07b6be12d005a0ed0c5c43b7bedbf3 git Not specified
CNA Linux Linux affected c0b11dc50590e10590b39dcda79835cd32f49d00 git Not specified
CNA Linux Linux affected 4c12c3c8abd8b888945d31e7bdbb0d8b73032fc5 git Not specified
CNA Linux Linux affected 25d8e065c7972dc98fd7a4cac322d5367eaede88 git Not specified
CNA Linux Linux affected 4a855c5aec41bf84922224ab7a74e088776e3ac4 git Not specified
CNA Linux Linux affected a9f0407414e16176fdbbbd298c9e18d6dfdf96bc git Not specified
CNA Linux Linux affected 6.12.16 6.13 semver Not specified
CNA Linux Linux affected 6.13.4 6.14 semver Not specified
CNA Linux Linux affected 5.15.179 5.16 semver Not specified
CNA Linux Linux affected 6.1.130 6.2 semver Not specified
CNA Linux Linux affected 6.6.81 6.7 semver Not specified
CNA Linux Linux affected 5.10.235 5.11 semver Not specified
CNA Linux Linux affected 6.14 Not specified
CNA Linux Linux unaffected 6.14 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/87cd6b717e4069dca34e0866e57eaeb44d3b173e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/36c07127924f11fc5741a780abcaaf808fe9ef13 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

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