In the Linux kernel, the following vulnerability has been resolved:

tls: fix missing memory barrier in tls_init

In tls_init(), a write memory barrier is missing, and store-store
reordering may cause NULL dereference in tls_{setsockopt,getsockopt}.

CPU0                               CPU1
-----                              -----
// In tls_init()
// In tls_ctx_create()
ctx = kzalloc()
ctx->sk_proto = READ_ONCE(sk->sk_prot) -(1)

// In update_sk_prot()
WRITE_ONCE(sk->sk_prot, tls_prots)     -(2)

                                   // In sock_common_setsockopt()
                                   READ_ONCE(sk->sk_prot)->setsockopt()

                                   // In tls_{setsockopt,getsockopt}()
                                   ctx->sk_proto->setsockopt()    -(3)

In the above scenario, when (1) and (2) are reordered, (3) can observe
the NULL value of ctx->sk_proto, causing NULL dereference.

To fix it, we rely on rcu_assign_pointer() which implies the release
barrier semantic. By moving rcu_assign_pointer() after ctx->sk_proto is
initialized, we can ensure that ctx->sk_proto are visible when
changing sk->sk_prot.

kernel.org https://git.kernel.org/stable/c/2c260a24cf1c4d30ea3646124f766ee46169280b [No types assigned]

kernel.org https://git.kernel.org/stable/c/335c8f1566d8e44c384d16b450a18554896d4e8b [No types assigned]

kernel.org https://git.kernel.org/stable/c/91e61dd7a0af660408e87372d8330ceb218be302 [No types assigned]

kernel.org https://git.kernel.org/stable/c/ab67c2fd3d070a21914d0c31319d3858ab4e199c [No types assigned]

kernel.org https://git.kernel.org/stable/c/d72e126e9a36d3d33889829df8fc90100bb0e071 [No types assigned]

kernel.org https://git.kernel.org/stable/c/ef21007a7b581c7fe64d5a10c320880a033c837b [No types assigned]