ipv6: ioam: refresh hdr pointer before ioam6_event()

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Summary

CVECVE-2026-64132
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-19 16:17:55 UTC
Updated2026-07-19 16:17:55 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ipv6: ioam: refresh hdr pointer before ioam6_event() Reported by Sashiko: In ipv6_hop_ioam(), the hdr pointer is initialized to point into the skb's linear data buffer. Later, the code calls skb_ensure_writable(), which might reallocate the buffer: if (skb_ensure_writable(skb, optoff + 2 + hdr->opt_len)) goto drop; /* Trace pointer may have changed */ trace = (struct ioam6_trace_hdr *)(skb_network_header(skb) + optoff + sizeof(*hdr)); ioam6_fill_trace_data(skb, ns, trace, true); ioam6_event(IOAM6_EVENT_TRACE, dev_net(skb->dev), GFP_ATOMIC, (void *)trace, hdr->opt_len - 2); If the skb is cloned or lacks sufficient linear headroom, skb_ensure_writable() will invoke pskb_expand_head(), which reallocates the skb's data buffer and frees the old one, invalidating pointers to it. While the code recalculates the trace pointer immediately after the call to skb_ensure_writable(), it fails to recalculate the hdr pointer. This patch fixes the above by recalculating the hdr pointer before passing hdr->opt_len to ioam6_event(), so that we avoid any UaF.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected f655c78d6225f585ef60a9d93ffb79d507ff3ad3 769723124b7c3b2bfea4cf68ad292698b87c8d01 git Not specified
CNA Linux Linux affected f655c78d6225f585ef60a9d93ffb79d507ff3ad3 24de676da63c1122d2c13b0d546238b66d1b4e62 git Not specified
CNA Linux Linux affected f655c78d6225f585ef60a9d93ffb79d507ff3ad3 5af905aa8e91ff8d94572a1e089558f21dcf24ed git Not specified
CNA Linux Linux affected f655c78d6225f585ef60a9d93ffb79d507ff3ad3 e46e6bc97fb1f339730ff1ba74267fbf48e7a422 git Not specified
CNA Linux Linux affected 6.9 Not specified
CNA Linux Linux unaffected 6.9 semver Not specified
CNA Linux Linux unaffected 6.12.92 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.34 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.11 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/5af905aa8e91ff8d94572a1e089558f21dcf24ed 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/24de676da63c1122d2c13b0d546238b66d1b4e62 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e46e6bc97fb1f339730ff1ba74267fbf48e7a422 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/769723124b7c3b2bfea4cf68ad292698b87c8d01 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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