From: Matt Bobrowski Date: Thu, 9 Jul 2026 02:53:16 +0000 (+0000) Subject: bpf: Fix UAF in sock clone early bailouts X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7cbd0c4cebe4c9f678d15e6b9ba975e1155a107f;p=thirdparty%2Fkernel%2Flinux.git 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(). Fixes: 6ac99e8f23d4 ("bpf: Introduce bpf sk local storage") Fixes: f12dd75959b0 ("bpf: net: Set sk_bpf_storage back to NULL for cloned sk") Signed-off-by: Matt Bobrowski Signed-off-by: Daniel Borkmann Reviewed-by: Kuniyuki Iwashima Acked-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20260709025316.999913-1-mattbobrowski@google.com --- diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c index ecd659f79fd4..1d295a8769fa 100644 --- a/net/core/bpf_sk_storage.c +++ b/net/core/bpf_sk_storage.c @@ -158,8 +158,6 @@ int bpf_sk_storage_clone(const struct sock *sk, struct sock *newsk) struct bpf_local_storage_elem *selem; int ret = 0; - RCU_INIT_POINTER(newsk->sk_bpf_storage, NULL); - rcu_read_lock_dont_migrate(); sk_storage = rcu_dereference(sk->sk_bpf_storage); diff --git a/net/core/sock.c b/net/core/sock.c index 8a59bfaa8096..498a57f34f5b 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2492,6 +2492,9 @@ struct sock *sk_clone(const struct sock *sk, const gfp_t priority, sock_copy(newsk, sk); newsk->sk_prot_creator = prot; +#ifdef CONFIG_BPF_SYSCALL + RCU_INIT_POINTER(newsk->sk_bpf_storage, NULL); +#endif /* SANITY */ if (likely(newsk->sk_net_refcnt)) {