Description
In the Linux kernel, the following vulnerability has been resolved: ipv6: account for fraggap on the paged allocation path In __ip6_append_data(), when the paged-allocation branch is taken (MSG_MORE / NETIF_F_SG / large fraglen), alloclen and pagedlen are computed as alloclen = fragheaderlen + transhdrlen; pagedlen = datalen - transhdrlen; datalen already includes fraggap (datalen = length + fraggap). When fraggap is non-zero, this is not the first skb and transhdrlen is zero. The fraggap bytes carried over from the previous skb are copied just past the fragment headers in the new skb's linear area. The linear area is therefore undersized by fraggap bytes while pagedlen is overstated by the same amount, and the copy writes past skb->end into the trailing skb_shared_info. An unprivileged user can trigger this via a UDPv6 socket using MSG_MORE together with MSG_SPLICE_PAGES. The bad accounting was introduced by commit 773ba4fe9104 ("ipv6: avoid partial copy for zc"). Before commit ce650a166335 ("udp6: Fix __ip6_append_data()'s handling of MSG_SPLICE_PAGES"), the negative copy value caused -EINVAL to be returned. That later commit allowed MSG_SPLICE_PAGES to proceed in this case, making the corruption triggerable. The non-paged branch sets alloclen to fraglen, which already accounts for fraggap because datalen does. Bring the paged branch in line by adding fraggap to alloclen and subtracting it from pagedlen. After this adjustment, copy no longer collapses to -fraggap on the paged path, so remove the stale comment describing that old arithmetic. Since a negative copy is no longer expected for a valid MSG_SPLICE_PAGES case, remove the MSG_SPLICE_PAGES exception from the negative copy check.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
773ba4fe9104a64a54d1c00f0fb6ffb95def2b03 to < 14200d435af9a9eeb444f529fc2f689a236b7962affected773ba4fe9104a64a54d1c00f0fb6ffb95def2b03 to < 65fb14cbebb0cd0eff903a22d33537ddc8b95769affected773ba4fe9104a64a54d1c00f0fb6ffb95def2b03 to < 46f201f8b4c39633a1fa3dc12459f506d470993daffected773ba4fe9104a64a54d1c00f0fb6ffb95def2b03 to < 6374fb9edf72c67a118a2c214a0dddd04c921e0aaffected773ba4fe9104a64a54d1c00f0fb6ffb95def2b03 to < e9eacf19281ea2498b36291b56c9606118c2d74eaffected773ba4fe9104a64a54d1c00f0fb6ffb95def2b03 to < 736b380e28d0480c7bc3e022f1950f31fe53a7c5affected
Linux Linux
Default version status: affected
6.0affected0 to < 6.0unaffected6.1.177 to ≤ 6.1.*unaffected6.6.144 to ≤ 6.6.*unaffected6.12.95 to ≤ 6.12.*unaffected6.18.38 to ≤ 6.18.*unaffected7.1.3 to ≤ 7.1.*unaffected7.2 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/14200d435af9a9eeb444f529fc2f689a236b7962 ↗
- https://git.kernel.org/stable/c/65fb14cbebb0cd0eff903a22d33537ddc8b95769 ↗
- https://git.kernel.org/stable/c/46f201f8b4c39633a1fa3dc12459f506d470993d ↗
- https://git.kernel.org/stable/c/6374fb9edf72c67a118a2c214a0dddd04c921e0a ↗
- https://git.kernel.org/stable/c/e9eacf19281ea2498b36291b56c9606118c2d74e ↗
- https://git.kernel.org/stable/c/736b380e28d0480c7bc3e022f1950f31fe53a7c5 ↗
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-53362 ↗
- https://cert-portal.siemens.com/productcert/html/ssa-784472.html ↗