Medium [CVE-2026-68399] Use-After-Free vulnerability in BPF socket cloning

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix UAF in sock clone early bailouts Similar to recent commit 9b51a6155d14 ("bpf,fork: wipe ->bpf_storage before bailouts that access it"), sk_clone() performs an initial shallow copy of the socket field ->sk_bpf_storage via sock_copy() for the cloned socket newsk.

If sk_clone() bails out early (e.g. if sk_filter_charge() fails) prior to calling bpf_sk_storage_clone(), newsk->sk_bpf_storage still points to the parent socket's BPF local storage.

When newsk is subsequently freed via sk_free(), the deallocation path (__sk_destruct() -> bpf_sk_storage_free()) destroys the parent socket's BPF local storage, leading to a use-after-free (UAF) on the parent socket.

Fix this by resetting newsk->sk_bpf_storage to NULL immediately after sock_copy() in sk_clone(), and remove the now redundant initialization from bpf_sk_storage_clone(). A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) component, specifically within the socket cloning mechanism.

When a new socket is created and its cloning process fails prematurely, the new socket's BPF local storage may incorrectly reference the parent socket's storage. An attacker could potentially exploit this to cause a system crash (denial of service) or achieve arbitrary code execution.