Description
In the Linux kernel, the following vulnerability has been resolved: net: fix fanout UAF in packet_release() via NETDEV_UP race `packet_release()` has a race window where `NETDEV_UP` can re-register a socket into a fanout group's `arr[]` array. The re-registration is not cleaned up by `fanout_release()`, leaving a dangling pointer in the fanout array. `packet_release()` does NOT zero `po->num` in its `bind_lock` section. After releasing `bind_lock`, `po->num` is still non-zero and `po->ifindex` still matches the bound device. A concurrent `packet_notifier(NETDEV_UP)` that already found the socket in `sklist` can re-register the hook. For fanout sockets, this re-registration calls `__fanout_link(sk, po)` which adds the socket back into `f->arr[]` and increments `f->num_members`, but does NOT increment `f->sk_ref`. The fix sets `po->num` to zero in `packet_release` while `bind_lock` is held to prevent NETDEV_UP from linking, preventing the race window. This bug was found following an additional audit with Claude Code based on CVE-2025-38617.
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
ce06b03e60fc19c680d1bf873e779bf11c2fc518 to < ee642b1962caa9aa231c01abbd58bc453ae6b66eaffectedce06b03e60fc19c680d1bf873e779bf11c2fc518 to < 42cfd7898eeed290c9fb73f732af1f7d6b0a703eaffectedce06b03e60fc19c680d1bf873e779bf11c2fc518 to < 1b4c03f8892d955385c202009af7485364731bb9affectedce06b03e60fc19c680d1bf873e779bf11c2fc518 to < 654386baef228c2992dbf604c819e4c7c35fc71baffectedce06b03e60fc19c680d1bf873e779bf11c2fc518 to < 75fe6db23705a1d55160081f7b37db9665b1880baffectedce06b03e60fc19c680d1bf873e779bf11c2fc518 to < d0c7cdc15fdf8c4f91aca1928e52295d175b6ec6affectedce06b03e60fc19c680d1bf873e779bf11c2fc518 to < ceccbfc6de720ad633519a226715989cfb065af1affectedce06b03e60fc19c680d1bf873e779bf11c2fc518 to < 42156f93d123436f2a27c468f18c966b7e5db796affected
Linux Linux
Default version status: affected
3.1affected0 to < 3.1unaffected5.10.253 to ≤ 5.10.*unaffected5.15.203 to ≤ 5.15.*unaffected6.1.168 to ≤ 6.1.*unaffected6.6.131 to ≤ 6.6.*unaffected6.12.80 to ≤ 6.12.*unaffected6.18.21 to ≤ 6.18.*unaffected6.19.11 to ≤ 6.19.*unaffected7.0 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/ee642b1962caa9aa231c01abbd58bc453ae6b66e ↗
- https://git.kernel.org/stable/c/42cfd7898eeed290c9fb73f732af1f7d6b0a703e ↗
- https://git.kernel.org/stable/c/1b4c03f8892d955385c202009af7485364731bb9 ↗
- https://git.kernel.org/stable/c/654386baef228c2992dbf604c819e4c7c35fc71b ↗
- https://git.kernel.org/stable/c/75fe6db23705a1d55160081f7b37db9665b1880b ↗
- https://git.kernel.org/stable/c/d0c7cdc15fdf8c4f91aca1928e52295d175b6ec6 ↗
- https://git.kernel.org/stable/c/ceccbfc6de720ad633519a226715989cfb065af1 ↗
- https://git.kernel.org/stable/c/42156f93d123436f2a27c468f18c966b7e5db796 ↗
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html ↗
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html ↗
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html ↗