Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
ipv6: fix use-after-free in ip6_finish_output2()
ip6_finish_output2() caches a pointer to the IPv6 destination address (daddr) before invoking lwtunnel_xmit(). The LWT-BPF transmit path or other encapsulation operations within lwtunnel_xmit() can reallocate the skb head, freeing the memory that daddr points to. When lwtunnel_xmit() returns LWTUNNEL_XMIT_CONTINUE, the function continues to use the stale daddr pointer to compute the nexthop and to look up or create the neighbour entry. This results in a use-after-free read, which can leak sensitive kernel data, pollute the neighbour table with arbitrary values, misdirect traffic, or crash the system.
Fix this by re-fetching the IPv6 header and the destination address pointer after lwtunnel_xmit() returns LWTUNNEL_XMIT_CONTINUE, ensuring that the subsequent nexthop computation and neighbour lookup operate on valid memory.
Details
- Affected product:
- AlmaLinux 9.2 ESU , Debian 11 ELS , TuxCare 9.6 ESU , TuxCare 9.8 ESU
- Affected packages:
- kernel @ 5.14.0 (+3 more)
Fixes
KernelCare state
Live-patch status from KernelCare for each operating system.
| Operating system | Status | Covered kernels |
|---|---|---|
| Debian 12 | Released |
43 kernels
|
| Oracle Linux 8 UEK 7 | Planned | — |
| Oracle Linux 9 UEK 7 | In Rollout |
114 kernels
|
| RHEL 9 | Planned | — |