CVE-2024-36489 Information

Description

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_setsockoptgetsockopt.

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_setsockoptgetsockopt()
                               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.

Reference

https://git.kernel.org/stable/c/d72e126e9a36d3d33889829df8fc90100bb0e071 https://git.kernel.org/stable/c/2c260a24cf1c4d30ea3646124f766ee46169280b https://git.kernel.org/stable/c/335c8f1566d8e44c384d16b450a18554896d4e8b https://git.kernel.org/stable/c/ab67c2fd3d070a21914d0c31319d3858ab4e199c https://git.kernel.org/stable/c/ef21007a7b581c7fe64d5a10c320880a033c837b https://git.kernel.org/stable/c/91e61dd7a0af660408e87372d8330ceb218be302