CVE-2024-36489 tls: fix missing memory barrier in tls_init
A missing memory barrier in the Linux kernel TLS initialization can lead to a NULL pointer dereference, causing a denial of service.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2024-36489?
CVE-2024-36489 is a medium-severity vulnerability in Linux kernel, published on 21 Jun 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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_{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.
Weakness: CWE-476
Which versions are affected by CVE-2024-36489?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2024-36489?
Apply the vendor's patch.
Is CVE-2024-36489 being exploited?
There is no known exploitation of CVE-2024-36489 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2024-36489, DEBIAN-CVE-2024-36489, GHSA-692g-7998-j2vj, UBUNTU-CVE-2024-36489.